1. Teacher’s Guide
5
PSEC_5_Teacher's Guide_P001-204.indd 1 1/29/19 09:39

2. 58 St Aldates
Oxford
OX1 1ST
United Kingdom
Pathway to Science Teacher’s Guide Level 5
First Edition: 2014
ISBN: 978-607-06-0968-8
Pathway to Science 5 is a collaborative work, created and designed by
the Department of Educational Research of Santillana.
© Richmond Publishing, S.A. de C.V. 2014
Av. Río Mixcoac No. 274, Col. Acacias,
Del. Benito Juárez, C.P. 03240, México, D.F.
Publisher: Justine Piekarowicz
Editor: Dominic Wright
Art and Design Coordinator: Marisela Pérez
Pre-Press Coordinator: Daniel Santillán
Cover Design: Erika Martínez
Cover Photograph: iStockphoto, Octopus eye
All rights reserved. No part of this work may be reproduced, stored in
a retrieval system or transmitted in any form or by any means without
prior written permission from the Publisher.
Richmond publications may contain links to third party websites or
apps. We have no control over the content of these websites or apps,
which may change frequently, and we are not responsible for the
content or the way it may be used with our materials. Teachers and
students are advised to exercise discretion when accessing the links.
The Publisher has made every effort to trace the owner of copyright
material; however, the Publisher will correct any involuntary omission at
the earliest opportunity.
First published by Santillana del Pacífico S.A. de Ediciones
Printed in Mexico by
First Edition in Ecuador: 2019
ISBN: 978-9942-31-235-8
Printed in: Imprenta Mariscal
Editor: Dominic Wright, María del Carmen García
PSEC_5_Teacher's Guide_P001-204.indd 2 1/29/19 09:39

3. Table of Contents
Components of Pathway to Science for the Teacher .................. 4
Teacher’s Guide Organization ....................................................... 5
Student’s Book Organization ......................................................... 6
Digital Book...................................................................................... 9
Student’s Book Table of Contents................................................ 10
• Unit 1........................................................................................ 12
• Unit 2........................................................................................ 64
• Unit 3........................................................................................ 98
• Unit 4...................................................................................... 140
Glossary ........................................................................................ 178
Cutouts.......................................................................................... 185
Activity Cards............................................................................... 196
Scientific Research Skills............................................................ 202
Notes ............................................................................................. 203
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4. 1. Teacher’s Guide: The Teacher’s Guide contains the Student’s Book presented in
a smaller format with an annotated answer key. Other features include key language,
language extension activities, common mistakes and possible difficulties, explanations
of science concepts and suggestions for related apps.
2. Books with Printable Worksheets and Evaluations
• A book with two reinforcement and two extension worksheets per unit.
• A book with a choice of two evaluations per unit. Each item is based on a learning
objective, a specific skill and content from the Student’s Book so that the validity
of the evaluations is guaranteed.
• Books with Printable Worksheets and Evaluations at www.santillanadigital.com
Components of Pathway to Science
for the Teacher
Unit 1 Pathway to Science 5
D.R. © Richmond Publishing, S.A. de C.V., 2014
Name: Class: Date:
1. The hematocrit, or packed cell volume (PCV), is the percentage of the volume of red blood cells to
the total volume of blood. Hematocrit values for men vary between 42 % and 52 %. For women, they
are between 37 % and 47 %. Three adults were given a blood test. Below are the results.
Use the information to answer the questions.
a. Which patient has a normal hematocrit percentage?
b. Which patients have an abnormal hematocrit percentage?
c. Which blood components are not analyzed in this test? What are the functions of these elements?
d. Make a bar graph in your notebook that compares the results of each patient with the normal values.
Name of Patient David Victoria Tom
Hematocrit (%) 36 45 58
Extension Worksheet 1
Fichas PS 5.indd 8 10/24/13 10:59 AM
Unit 1 Pathway to Science 5
D.R. © Richmond Publishing, S.A. de C.V., 2014
Name: Class: Date:
1. A group of students measured the digestion time of certain nutrients and recorded the results.
Time (minutes)
Remaining Nutrients
Carbohydrates (grams) Proteins (grams) Lipids (grams)
10 30 30 30
20 15 25 27
30 5 20 24
Use the information to respond.
a. Which nutrient is digested the fastest? Which is digested the most slowly?
b. The digestion of each nutrient starts in a different organ: the mouth, stomach and small intestine.
Which organ do you think starts the digestion of each nutrient? Why?
c. Using the information in the table, make three line graphs.
Extension Worksheet 2
Fichas PS 5.indd 9 10/24/13 11
PSEC_5_Reinforcement-Worksheets_P001-032.indd 8 16/1/19 12:45
Unit 1 Pathway to Science 5
D.R. © Richmond Publishing, S.A. de C.V., 2014
Name: Class: Date:
1. Look at the images and complete the table with the correct level of biological organization and
its description.
Level of Biological Organization Description
Reinforcement Worksheet 1
Fichas PS 5.indd 4 10/21/13 5:14 PM
Unit 1 Pathway to Science 5
D.R. © Richmond Publishing, S.A. de C.V., 2014
2. Read the sentences and write T for true and F for false. Explain your answers.
a. Intestinal villi absorb nutrients from food.
b. Egestion is the stage of digestion when feces are eliminated.
c. The small intestine mixes food with gastric juices to form chyle.
d. The bolus becomes chyme after passing through the stomach.
e. Ingestion occurs when food enters the mouth.
f. Bile is a substance secreted by the pancreas.
g. The cardiac sphincter allows the bolus to pass to the stomach
h. Peristaltic movements transport intestinal chyle.
i. The large intestine absorbs nutrients and water.
j. The digestive process starts when food is chewed and mixed with saliva.
k. As food passes through the digestive system, the amount of it increases.
Fichas PS 5.indd 5 10/21/13 5:14 PM
PSEC_5_Reinforcement-Worksheets_P001-032.indd 4 16/1/19 12:45
Unit 1 Evaluation
Pathway to Science 5
D.R. © Richmond Publishing, S.A. de C.V., 2014
Name: Class: Date:
Test A
Mark the correct answers with a .
1 Which level of biological organization includes all the others?
A. Tissue.
B. Cell.
C. Organ.
D. System.
2 Look at the image. Which level of organization does it belong to?
A. Tissue.
B. Cell.
C. Organ.
D. Organism.
3 A scientist analyzed a sample of cells in the lab and discovered that the cells carried out the same
function. Which level of organization does the sample belong to?
A. Tissue.
B. Cell.
C. Organ.
D. Organism.
U1 Evaluaciones PS 5.indd 4 10/21/13 4:59 PM
Unit 1 Test A
D.R. © Richmond Publishing, S.A. de C.V., 2014
Pathway to Science 5
4 Look at the images. From the least to the most complex, what is the order of the levels of biological
organization?
III
I II IV V
A. III – I – V – II – IV
B. IV – II – V – I – III
C. I – III – V – II – IV
D. IV – II – V – III – I
5 Which sentence describes a multicellular organism?
A. The cells form colonies.
B. The organism has tissue.
C. The organism has only one cell.
D. It can only be seen by a microscope.
6 In what order does food pass through these digestive organs?
1. Anus. 3. Esophagus. 5. Small intestine.
2. Mouth. 4. Stomach.
A. 2 – 4 – 3 – 5 – 1
B. 2 – 3 – 4 – 5 – 1
C. 1 – 5 – 3 – 4 – 2
D. 1 – 5 – 4 – 3 – 2
U1 Evaluaciones PS 5.indd 5 10/21/13 4:59 PM
PSEC_5_Evaluations_P001-088.indd 5 15/1/19 13:40
Unit 1 Evaluation
Pathway to Science 5
D.R. © Richmond Publishing, S.A. de C.V., 2014
Name: Class: Date:
Test A
Mark the correct answers with a .
1 Which level of biological organization includes all the others?
A. Tissue.
B. Cell.
C. Organ.
D. System.
2 Look at the image. Which level of organization does it belong to?
A. Tissue.
B. Cell.
C. Organ.
D. Organism.
3 A scientist analyzed a sample of cells in the lab and discovered that the cells carried out the same
function. Which level of organization does the sample belong to?
A. Tissue.
B. Cell.
C. Organ.
D. Organism.
U1 Evaluaciones PS 5.indd 4 10/21/13 4:59 PM
Unit 1 Test A
D.R. © Richmond Publishing, S.A. de C.V., 2014
Pathway to Science 5
4 Look at the images. From the least to the most complex, what is the order of the levels of biological
organization?
III
I II IV V
A. III – I – V – II – IV
B. IV – II – V – I – III
C. I – III – V – II – IV
D. IV – II – V – III – I
5 Which sentence describes a multicellular organism?
A. The cells form colonies.
B. The organism has tissue.
C. The organism has only one cell.
D. It can only be seen by a microscope.
6 In what order does food pass through these digestive organs?
1. Anus. 3. Esophagus. 5. Small intestine.
2. Mouth. 4. Stomach.
A. 2 – 4 – 3 – 5 – 1
B. 2 – 3 – 4 – 5 – 1
C. 1 – 5 – 3 – 4 – 2
D. 1 – 5 – 4 – 3 – 2
U1 Evaluaciones PS 5.indd 5 10/21/13 4:59 PM
PSEC_5_Evaluations_P001-088.indd 4 15/1/19 13:40
4
PSEC_5_Teacher's Guide_P001-204.indd 4 1/29/19 09:39

5. Pathway to Science 5
Richmond Publishing, S.A. de C.V., 2014
Date:
nts and recorded the results.
ients
ms) Lipids (grams)
30
27
24
most slowly?
outh, stomach and small intestine.
Why?
2
10/24/13 11:00 AM
Answer Key and Teaching Notes
• Section Organization
• Clarifying Concepts
• Common Mistakes
• Possible Difficulties
• In 5 minutes
Teacher’s Guide Organization
• Initial Evaluation
• A Healthy Lifestyle
• Being Safe
• Taking Care of the
Planet
• Recommended Apps
Point out that the energy sources
on page 89 are renewable and
generally clean ways of generating
electricity. Ask students to look at
the table on page 88 and discuss
the nonrenewable energy sources
they see, as well as others they
know. Ask: Which of these are bad
for the environment? Why?
Language Extension
man-made lake
that stores water
Wind farms use the kinetic energy of the
wind to move the blades of wind turbines
and generate electric energy.
Hydroelectric dams use gravitational potential
energy. Water is contained in a large reservoir
at high altitude. When it falls, it turns giant
wheels that generate electric energy.
Renewable Energy Sources
Where does the electricity come from to turn on the TV? Electricity powers all the
electric devices in our homes, like our televisions, stereos and video game consoles.
A lot of electricity comes from nonrenewable sources, such as petroleum, coal
and natural gas. However, it is now possible to generate electricity from various
renewable sources, like the wind, ocean or sun. Electric energy is produced by
electricity generators. The principal generators of renewable energy are:
Our population has grown and technology has advanced in recent years, increasing the need for electricity. It is now
necessary to find alternative energy sources that do not harm the environment, like solar and wind power.
Education through Values
Solar energy plants use the radiant energy of
the sun. Chemical reactions in solar panels
turn this natural energy into electric energy.
Principal Renewable
Energy Generators
relating to rays
or waves
Recognize changes in electric energy and scientific contributions to our
knowledge of electricity
Chinaishometothelargest
wind farms in the world.
Fun Fact!
center
Geothermal energy plants use the heat from
the earth’s core to generate electric energy.
89
Physics and Chemistry
This information is presented
to promote respect for the
environment. Discuss the impact
that these energy generators have
on the environment, the costs
involved and their importance to
produce energy for humans. Ask
students to think of ways they can
protect the environment and use
energy efficiently at home.
Education through Values
101
Physics and Chemistry
Notes
Answer Key and Teaching Notes Pathway to Science 5
U3 PStg5.indd 101 3/23/15 3:02 PM
When discussing energy in this
context, students may tend to
think that this energy is different
from the energy related to living
things seen in previous units.
Emphasize that it is the same
energy but it can also manifest in
different ways.
Clarifying Concepts
Vocabulary nouns: coal,
conductor, core, dam, energy,
fan, flag, food, generator,
glass, heater, hiker, light, plant,
reservoir, sound, stove, turbine,
wind
verbs: emit, generate, transport
adjectives: chemical,
gravitational, hydraulic, kinetic,
nonrenewable, principal, radiant,
renewable, solar, thermal, vital
Skill Students can discuss
and compare renewable and
nonrenewable energy sources
Language Focus
ventilator
Section
1 Electric Energy
1
Energy in Our Surroundings
Do you need energy to open and close your eyes? Yes, you do! You even need
energy to sleep. All living things need energy to complete their vital functions.
This energy comes from nutrients in food. Energy is also needed for a TV to
turn on or a car to start.
Energy can be found in many places. It is defined as the ability to produce
changes in the properties or movements of a body or an object—for example,
it is used when you go from walking to running or turn on a fan.
Read about the different forms of energy in the chart below.
Connecting
walker
Form of Energy Example
Gravitational potential
Found in objects or people when they are at
a certain height.
A hiker on a mountain or a glass on a
table.
Chemical Contained in chemical substances. Food, coal, wood or batteries.
Kinetic Found in bodies or objects in motion. A car driving on the road.
Wind Generated by the wind. A flag moving in the wind.
Electric
Produces the movement of electric charge
through a conductor.
A television, computer or microwave.
Thermal Produced by heat. A stove, a heater or hot water.
Hydraulic Generated by the movement of water. Dams and reservoirs.
Light Emitted by objects in the form of light. A lightbulb or the sun.
Sound Transports sound. A guitar.
88 Unit 3
E
e
T
t
c
UNIT 3:
ELECTRICITY
Section 1: Electric Energy
• Energy in Our Surroundings
• Renewable Energy Sources
• Changes in Electric Energy
• Electricity: The Important Scientists
Section Organization
100 Unit 3
U3 PStg5.indd 100 11/13/13 5:47 PM
Point out that the energy sources
on page 89 are renewable and
generally clean ways of generating
electricity. Ask students to look at
the table on page 88 and discuss
the nonrenewable energy sources
they see, as well as others they
know. Ask: Which of these are bad
for the environment? Why?
Language Extension
man-made lake
that stores water
Wind farms use the kinetic energy of the
wind to move the blades of wind turbines
and generate electric energy.
Hydroelectric dams use gravitational potential
energy. Water is contained in a large reservoir
at high altitude. When it falls, it turns giant
wheels that generate electric energy.
Renewable Energy Sources
Where does the electricity come from to turn on the TV? Electricity powers all the
electric devices in our homes, like our televisions, stereos and video game consoles.
A lot of electricity comes from nonrenewable sources, such as petroleum, coal
and natural gas. However, it is now possible to generate electricity from various
renewable sources, like the wind, ocean or sun. Electric energy is produced by
electricity generators. The principal generators of renewable energy are:
Our population has grown and technology has advanced in recent years, increasing the need for electricity. It is now
necessary to find alternative energy sources that do not harm the environment, like solar and wind power.
Education through Values
Solar energy plants use the radiant energy of
the sun. Chemical reactions in solar panels
turn this natural energy into electric energy.
Principal Renewable
Energy Generators
relating to rays
or waves
Recognize changes in electric energy and scientific contributions to our
knowledge of electricity
Chinaishometothelargest
wind farms in the world.
Fun Fact!
center
Geothermal energy plants use the heat from
the earth’s core to generate electric energy.
89
Physics and Chemistry
This information is presented
to promote respect for the
environment. Discuss the impact
that these energy generators have
on the environment, the costs
involved and their importance to
produce energy for humans. Ask
students to think of ways they can
protect the environment and use
energy efficiently at home.
Education through Values
101
Physics and Chemistry
Notes
Answer Key and Teaching Notes Pathway to Science 5
U3 PStg5.indd 101 3/23/15 3:02 PM
CN.3.3.11. To analyze the transformations of energy, from its generation to its conversion.
PSEC_5_Teacher's Guide_P001-204.indd 100 22/1/19 09:44
Case 1 Case 2 Case 3
Does the flashlight
turn on?
in the wrong direction
a red-brown
metal
What Do You Know? Initial Evaluation
1. Mark all the objects that need electricity with a .
2. Mark dangerous situations with an .
Scientific Skill: Compare predictions with results
3. Look at the photograph and answer the questions.
a. Make a prediction for each case.
Case 1: Would the flashlight turn on if it had only one battery?
Case 2: Would the flashlight turn on if one of the batteries were placed backward?
Case 3: Would the flashlight turn on if there were a piece of copper between the batteries?
b. Collect a flashlight, two batteries and a piece of copper. Test each of the cases above. Record your results
in the table.
c. Compare your results with your predictions. Are they the same? Explain why or why not.
87
Physics and Chemistry
U3 PSst5.indd 87 8/9/13 11:14 AM
Since this may be the first time
that students study electricity,
they may not be able to rely on
previous knowledge. They may
have different ideas about the
risks of misusing electrical
devices. Use their ideas and
experiences to answer the first
activities.
Initial Evaluation
Since the skill of predicting is
evaluated in question 3, students’
predictions will vary but all should
be considered correct. In this
activity, it is important that they
compare their results with their
predictions and that they are able
to explain their answers.
Initial Evaluation:
Scientific Skill
The Adventures of Alex – Electricity
(www.theadventuresofalex.com):
Join Alex, a smart and inquisitive
boy, in this fun story of his
quest to discover the origins of
electricity.
TeslaTown (www.tcipg.mste.
illinois.edu/applet/tt): Enter
Tesla Town and explore electricity
generation and delivery. Visit a
hydroelectric power plant, a solar-
powered house and a wind farm.
Recommended Apps
99
Physics and Chemistry
Notes
Answer Key and Teaching Notes Pathway to Science 5
The flashlight would not turn on because it needs two batteries to complete the circuit.
Copper is an conductor, so the flashlight would turn on.
No, because current in batteries flows in only one direction.
NO NO YES
Results should coincide with the predictions.
1.
Let’s Check!
points
8
points
6
1. Mark the devices that transform electric energy. Write the new form of energy below
each device.
2. Use the time line to record some principal contributions of scientists to the study of electricity.
(624–545 B.C.) (1847–1931)
108 Unit 3
U3 PSst5.indd 108 8/9/13 11:33 AM
Consider activity 1 successfully
completed if students obtain at
least six points.
Extra Support
Students should create a table
with the different forms of energy
that can be obtained from electric
energy and give an example device
for each case.
Evaluation Part 1
Consider activity 2 successfully
completed if students obtain at
least four points.
Extra Support
Students should create an
informative file about each
scientist, including their
contribution to the study of
electricity.
Evaluation Part 2
120 Unit 3
light and thermal wind and kinetic
kinetic and sound sound
Thales de Miletus
rubbed wool and
amber to attract
objects.
Benjamin Franklin
flew a kite to show
lightning is electrical.
Alessandro Volta
invented the first
electric battery.
Thomas Edison invented
lightbulbs and brought
electricity to homes.
1706 - 1790
1745 - 1827
Completing activities with the
cutouts boosts motivation for
students. Encourage independent
work and remember to supervise
the safe and correct use of
scissors.
Being Safe
In this section, students can
mention other components
previously studied.
Answer Key
Skill Students can perform and
explain the functions of a circuit
Language Focus Section 2 / Electric Circuits
1. Go to Cutout 11 on page 179. Glue each component of the home electricity network in the correct box. Identify
Measures the use of electricity. Opens or closes to allow
current to pass.
Transports electricity.
Where you plug in an
electric device.
Electrical switch that protects
against short circuits.
Sends electric current to all the
different circuits.
outlets
components:
Home Electricity Network
Practicing
Summarizing
102 Unit 3
U3 PSst5.indd 102 7/10/13 4:10 PM
114 Unit 3
switches cables circuit breaker meter
circuit breaker
switch
electricity meter
plug outlet box
electric cables
While reviewing these pages, ask
students where they think most
of the electricity is consumed in
the house (heating and cooling,
appliances). The goal is to get
students to think of ways of
saving energy.
Taking Care of the Planet
Materials: index cards
Form pairs. Have students draw
an image of each vocabulary term
from this lesson on an index card.
They should take turns showing a
card and quizzing each other on
its name and function, as well as
using it in a sentence. You can
include vocabulary from the other
lessons in the unit if time. Allow
students to write the name and
function of each item on the back
of the card at the end.
Language Extension
malfunction
or error
Recognize and construct a simple electric circuit and explain its function
1
2
5
6
7
9
9 The electric current reaches the house through cables
called power lines.
6 A circuit breaker is an automatically operated electrical
switch that protects an electric circuit. It disconnects the
energy entering the house when there is a short circuit,
preventing damage to the whole electricity network.
7 The switches open or close to allow current
to pass to different parts of the house.
8 The electric cables transport the energy throughout the
house.
Electricity can be measured
in volts, and each country
uses a different voltage
in their homes. Common
voltagesinclude120(Canada,
USA),127(Mexico),220(much
of Asia, South America and
Africa) and 230 (much of
Europe). Make sure to take
anadaptorwhenyoutravel!
Did You Know...?
101
Physics and Chemistry
U3 PSst5.indd 101 7/10/13 4:10 PM
113
Physics and Chemistry
Notes
Answer Key and Teaching Notes Pathway to Science 5
• Some pages include the skills required by the
Ecuadorian Ministry of Education. The skills are found
at the bottom of the page with their corresponding code.
The digital lessons correspond to topics from the Ecuadorian
curriculum that are not found in the book. Lessons with
answers are found in the Santillana Teacher’s Platform.
Digital Lessons
5
PSEC_5_Teacher's Guide_P001-204.indd 5 1/29/19 09:39

6. Quiz Yourself
Describe the levels of biological organization
1. Number the levels 1–5 from least complex to most complex. Put in order
2. Which level of biological organization includes all the other levels? Explain
tissue organism cell organ system
1. Complete the following chart.
Multicellular organisms are the fifth level of biological organization. They
are living things with many biological systems that help them live and move.
Summarizing
Practicing
The Basic Levels of Biological Organization
Level Description Examples
Cell
Group of cells that work together.
heart, lungs
System
lion, lizard
Life Science 17
U1 PSst5.indd 17 7/10/13 4:04 PM
Section 1 / The Levels of Biological Organization
Organisms
Look at the following images.
The living things above are all multicellular organisms. At what level of biological
organization do you classify them? You will notice that they are different from the
previous levels. This is because they are all part of the fifth and final level: the
organism.
A multicellular organism consists of several biological systems that work together
to allow its body to function. A cat is an organism that has a digestive system, a
nervous system and a skeletal system, among others. They all help the cat move
and live.
Cats are multicellular
organisms that have all
five levels of biological
organization, from single
cells to a complete organism.
In this image, you can see
all five levels in relation to
the skeletal system.
Level 1
Bone Cell
Level 2
Bone Tissue
Level 3
Bone
Level 4
Skeletal System
Level 5
Cat
tiger
tree
turtle
grasshopper
palm tree
Connecting
Cats and other animals
have a skeletal system.
What is the equivalent
structure in a tree?
Challenge
Unit 1
16
U1 PSst5.indd 16 7/10/13 4:03 PM
Life Science
What Do You Know? Initial Evaluation
Go to Cutout 1 on page 165. Glue the names of the organs in the correct boxes.
1. Mark the function of each organ listed with a .
Scientific Skill: Predict
2. A scientist observes the following in a lab:
a. Circle the difference between the digestive tracts of the mice.
b. What are the possible side effects of an irregular digestive tract? (Situation 2)
Heart Lungs Stomach
Allow air to enter and exit
the body
Pumps blood to other parts
of the body
Helps digest food
9
Situation 1 Situation 2
The mouse has a normal digestive tract. The mouse has an irregular digestive tract.
Life Science
U1 PSst5.indd 9 8/9/13 10:40 AM
Unit 1
1
Unit
Body
Systems
In this unit you will learn to:
• describe the levels of biological organization.
• identify the basic structures and functions of the digestive system.
• identify the basic structures and functions of the circulatory system.
• identify the basic structures of the respiratory system and explain respiration.
• make predictions in an independent research experiment.
8
chest
Key Words
cell
function
system
convert
circulate
Unit 1
U1 PSst5.indd 8 7/10/13 4:02 PM
Initial Pages of the Unit
Sections organized by
Learning Objectives
Initial Evaluation
Number and title
of unit
Describe the levels of biological organization
1. Complete the table with the correct level of biological organization.
Compare and Contrast
Organs are the third level of biological organization. They are groups of tissues that work together.
Systems are the fourth level of biological organization. They are groups of organs that work together.
Summarizing
The nervous system is an example
of the fourth level of biological
organization. It is a group of organs
that allow us to control our senses
and other organs and systems.
spinal cord
Structure Neuron Muscle Brain Nervous System Leaves
Level
brain
Systems
The fourth level of biological organization
is a system. A system is a group of
organs that work together to perform
the same function.
Forexample,thenervoussystemconsists
of two principal organs: the brain and
the spinal cord. The two organs work
together to control other organs and
to adjust to the environment.
Practicing
Some structures, like skin,
hair and nails, form part of
theintegumentarysystem.
This system helps protect
our bodies.
Did You Know...?
Life Science 15
U1 PSst5.indd 15 7/10/13 4:03 PM
everything around you
execute
organs that clean the blood
Section 1 / The Levels of Biological Organization
epidermis
mesophyll
lens
retina
iris
The eye is an organ. It represents the
third level of biological organization.
What other examples of this level can
you think of?
Groups of tissues work together to perform the
same function. They form organs, like this leaf.
cornea
Organs
Have you ever heard of the lungs, kidneys or the heart? These are all examples
of organs: the third level of biological organization. An organ consists of various
groups of tissues working together to complete the same function. For example,
in plants, leaves are the organs responsible for photosynthesis. Leaves consist
of two types of tissues: the epidermis and the mesophyll.
Animal organs are more complex than plant organs. For example,
think of our eyes. They allow us to see light and our surroundings.
To perform this function, the eye has many types of tissues
and structures that work together to allow us to see.
The following image shows the structure of the eye.
Pay attention to the different tissues.
Connecting
Photosynthesis is the
process by which plants
produce food using
carbon dioxide, water
and sunlight.
Word Focus
Unit 1
14
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Sections Organized by Learning Objectives
Learning
Objectives
Student’s Book Organization
Pathway to Science 5 is organized into four units. In each unit you will find:
Title and subtitle of section
Section Organized by
Learning Objectives
• Connecting
• Exploring
• Practicing
• Summarizing
• Quiz Yourself
6
PSEC_5_Teacher's Guide_P001-204.indd 6 1/29/19 09:39

7. Pathway to Science 5
Features of Each Unit
close groups
6
7
oxygen
artery
capillaries
carbon dioxide
vein
Close-up of an alveolus.
Although some clean vehicles exist, most modes of transportation contaminate the air we breathe. We should try to
develop habits that do not contaminate the air. For example, you can ride a bicycle instead of getting a ride in a
car. Little things can help make the environment better for everyone!
Education through Values
6 Bronchial Tubes: As we travel through these tubes, they get
smaller and narrower. This allows air to reach the whole lung.
At the end of the tubes, there are clusters of small sacs.
7 Alveoli: We have reached the end of the respiratory system,
the alveoli. These are small clustered sacs, surrounded by
capillaries. Oxygen enters the blood to reach all the cells in the
body through the alveoli. Carbon dioxide (cell waste) travels
through the blood into the alveoli to exit the body. This process
is called gas exchange.
Identify the basic structures of the respiratory system and explain respiration
Cigarettesmokeharmssmokers’
lungs and the lungs of anyone
nearby. Damage includes loss
of the elasticity or flexibility
in the walls of the alveoli,
decreasing the amount of
oxygen absorbed by the blood.
Staying Healthy
Did you know that all scientific
words come from Latin? We
use the Latin singular and
plural endings for these words.
For example, there can be one
bronchus and two bronchi;
one alveolus and two alveoli.
Fun Fact!
Life Science 47
U1 PSst5.indd 47 7/10/13 4:06 PM
The stomach is a very
important part of the
digestive system. Its
movements and gastric
juices help convert food
into nutrients.
bolus
gastric juices
stomach
esophagus
cardiac sphincter
chyme
small intestine
Section 2 / The Digestive System
Digestion in the Stomach: The Process Continues
Does your stomach ever make noises after you eat? Or have you ever heard your
stomach growling when you are hungry? This happens because the stomach is
a muscular organ shaped like a bean, with walls that move to help process food.
The bolus of food moves through the esophagus to reach the stomach. Then
it goes through a valve located at the entrance of the stomach. This valve is
called the cardiac sphincter. Its function is to allow food to pass through to the
stomach and to prevent stomach contents from entering the esophagus.
When food gets to the stomach, it mixes with
gastric juices. Gastric juices help with digestion
—the transformation of food into nutrients. For
example, proteins are digested in this process.
Gastric juices and peristaltic movements convert
the bolus into a thick liquid called chyme. This
liquid then moves toward the small intestine.
Connecting
• The word growl
normally describes
thesoundadogmakes
whenitisangry.Growl
also means the noise
your stomach makes
whenyouarehungry!
• A sphincter is a ring-
shaped muscle that
regulates the passage
of substances from
one place to the next.
Word Focus
It is important not to eat too much of
certain foods like chocolate or spices.
Some foods can have negative effects on
the cardiac sphincter, pushing food and
gastric juices back into the esophagus.
Staying Healthy
Essential Basics Skills: To describe, with the support of models, the structure and function of the digestive system.
Unit 1
22
PSEC_5_SB_U1_P008-055.indd 22 1/8/19 5:59 PM
Circulatory System Components
The circulatory system consists of three large components that work
together to transport substances such as nutrients and waste through the
body. The three components are: the heart, blood and blood vessels, as
seen in the diagram below.
Blood: a liquid tissue found in
blood vessels; travels through
the organism to transport
substances such as nutrients,
oxygen and waste.
Blood Vessels: tubes that
transport blood to all
parts of the body.
The heart, blood and blood vessels are parts
of the circulatory system.
Identify the basic structures and functions of the circulatory system
In the 15th century, an
English doctor named
William Harvey was the
first to correctly describe
the relationship between
the heart, blood and blood
vessels. He said that blood
goes to all parts of the body
through the blood vessels
with the help of the heart.
Did You Know...?
Thecirculatorysystemmoves
a liquid (blood) through the
body. Name two different
systems in machinery or
other areas that have a
similar system. Compare
and contrast the systems.
Challenge
contract and
force to move
Heart: muscular organ that
contracts to pump blood
through the organism.
Life Science 35
U1 PSst5.indd 35 7/10/13 4:05 PM
unassisted vision
Section 3 / The Circulatory System
When you extract a sample of blood, it
is possible to study all its components.
plasma
formed
elements
Our Blood
Now that you know that blood travels to all parts of the body, have you
ever wondered what blood looks like? To the naked eye, it just looks
like a red liquid, but it is actually a liquid tissue consisting of cells. If
you extract blood from a person and examine it under a microscope,
you can see the cells. Remember that cells are very small.
Some animals, such as mollusks, have
blue blood. Their blood has a substance
called hemocyanin, which transports
oxygen and turns the blood blue.
Did You Know...?
Unit 1
36
U1 PSst5.indd 36 7/10/13 4:05 PM
Case 1 Case 2 Case 3
Does the flashlight
turn on?
in the wrong direction
a red-brown
metal
What Do You Know? Initial Evaluation
1. Mark all the objects that need electricity with a .
2. Mark dangerous situations with an .
Scientific Skill: Compare predictions with results
3. Look at the photograph and answer the questions.
a. Make a prediction for each case.
Case 1: Would the flashlight turn on if it had only one battery?
Case 2: Would the flashlight turn on if one of the batteries were placed backward?
Case 3: Would the flashlight turn on if there were a piece of copper between the batteries?
b. Collect a flashlight, two batteries and a piece of copper. Test each of the cases above. Record your results
in the table.
c. Compare your results with your predictions. Are they the same? Explain why or why not.
87
Physics and Chemistry
U3 PSst5.indd 87 8/9/13 11:14 AM
3
Unit
Electricity
86
In this unit you will learn to:
• recognize changes in electric energy and scientific contributions to our knowledge of electricity.
• recognize and construct a simple electric circuit and explain its function.
• recognize conductors and insulators of an electric current.
• explain the importance of electricity and promote its conservation and responsible use.
• formulate explanations by comparing your results with your predictions.
• value the use of alternative energy sources.
Key Words
transform
efficient
predict
device
safety
cable
electrician
power strip
plug
outlet
86 Unit 3
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Unit 3
Intermediate Evaluation
points
4
points
2
3. Match each image with its description.
A source of electric energy. It has one positive
and one negative pole.
4. Look at the images. For each one, write whether the remaining lightbulbs will still work if
one is removed. Explain why or why not in each case.
Receives and transforms electric energy into
another type of energy.
Used to open and close a circuit.
Transports the electric current and is a
conductor.
109
Physics and Chemistry
U3 PSst5.indd 109 7/10/13 4:11 PM
1.
Let’s Check!
points
8
points
6
1. Mark the devices that transform electric energy. Write the new form of energy below
each device.
2. Use the time line to record some principal contributions of scientists to the study of electricity.
(624–545 B.C.) (1847–1931)
108 Unit 3
U3 PSst5.indd 108 8/9/13 11:33 AM
3. Name three important contributions to the study of electric energy.
• .
• .
• .
4. Write the name and function of each part of the circuit.
Unit 3
Final Evaluation
points
3
points
8
point
1
5. In a home electricity network, this device stops the electric current when there is an error:
A. A high-tension tower.
B. An electricity meter.
C. A circuit breaker.
D. A switch.
121
Physics and Chemistry
U3 PSst5.indd 121 7/10/13 4:12 PM
What Did You Learn?
1. Identify the form(s) of energy in each of the images.
points
6
points
4
2. Mark the devices that need electric energy to function. Then write which type of energy the
electric energy is transformed into.
120 Unit 3
U3 PSst5.indd 120 3/10/15 4:01 PM
Evaluation Pages
• Education through
Values
• Staying Healthy
• Did You Know…?
• Word Focus
• Fun Fact!
• Challenge
• Skills included
• What Do You Know?
Initial Evaluation
• Let’s Check!
Intermediate Evaluation
• What Did You Learn?
Final Evaluation
7
PSEC_5_Teacher's Guide_P001-204.indd 7 1/29/19 09:39

8. Pathway to Science D.R. © Richmond Publishing, S.A. de C.V., 2014
Water is an important resource for human beings: it regulates the global temperature, irrigates crops
and helps us maintain good personal hygiene, among other functions.
Water has been polluted by many human activities, such as livestock farming, agriculture, domestic
activities and industrial activities. For this reason, it has been necessary to establish natural
reserves to protect this resource.
Everyone can help save and protect water with simple actions such as turning off the tap when
brushing your teeth and taking quick showers.
Photic Zone
Aphotic Zone
200 meters below
surface level
Surface of the Ocean
Oceans and lakes are important saltwater and freshwater reserves. In both cases, the difference in luminosity,
temperature and pressure in the water affect the diversity of life forms.
Tides: changes in the level of the sea.
Waves: swells of water usually caused by the wind.
Currents: movements of water similar to a river, under the ocean
and in different directions.
In the ocean, masses of water experience three types of movement:
Low Tide
High Tide
Water covers three-fourths of the surface of the planet. The majority
of this water is salt water, and a smaller part is fresh water. Salt water,
unlike fresh water, has a large quantity of dissolved minerals and salt
that gives it its taste.
Water is found in many forms: glaciers, polar ice caps,
oceans, rivers, lakes, groundwater and as clouds or
vapor in the atmosphere.
In the hydrologic cycle, or water cycle, water circulates
continuously between these different forms.
Test 4 Study Page • Summary Name: Grade:
Test 4 PSst5.indd 1 9/3/13 4:28 PM
small stones
Communicate evidence and conclusions of an experiment
Experimental Procedure
1. What variable are you working with? In other words, what is the independent
variable in this experiment?
The presence of pollution.
The effect of pollution on wildlife.
2. With four classmates, collect the following materials:
• 2 ten centimeter pieces of the aquatic plant elodea
• 2 glass jars of equal size
• 1 marker
• gravel
• 1 lamp
• 1 lightbulb
• cooking oil
• water
• 1 plastic syringe
• 1 ruler
3. Using the marker, label the jars 1 and 2.
4. Put the same amount of gravel in each jar. Then plant an elodea in each.
Make sure the elodea is firmly planted in the gravel.
5. Fill the jars with equal amounts of water, covering the plants completely.
Pour the water carefully so that the plant does not come out of the gravel.
6. Add oil to jar 2 with the syringe until a three-centimeter layer is formed. Be
careful while you do this.
7. Place the lamp on a table. Place both jars close to it and at the same distance
so that they receive the same amount of light.
8. Observe the experiment daily for one week and record any changes in the
Results section. What do you think will happen to the
elodea plant in each jar?
How can you relate these answers to
your predictions?
1 2
Earth and the Universe 151
U4 PSst5.indd 151 7/10/13 4:15 PM
deposits as waste
Science Lab
Basic Framework
Water pollution affects the environment and the living things that live there. For example, the pollution in a river changes
the properties of the water, severely affecting the organisms that use it as a home or a source of nutrition. In human
beings, water pollution causes serious health problems.
Observation
A group of students passing by a river observe that
in the area near a factory (image 1) that dumps
contaminants into the water, there is less wildlife
than in other parts of the river (image 2).
What do you think is causing the difference in the
number of living things in each part of the river?
Research Question
According to what you observed, mark the best research question for this situation.
What effects does pollution have on the quality of water in the river?
What effects does pollution have on the development of wildlife in the river?
Hypothesis
The presence of contaminants harms the development of wildlife inhabiting the river.
Predictions
Form two predictions about what is observed:
Prediction 1:
Prediction 2:
The Effects of Water Pollution on Living Things
Scientific Skill: Communicate and represent evidence
1 2
Unit 4
150
U4 PSst5.indd 150 7/10/13 4:15 PM
Pathway to Science.ec
Air Pathways in the Respiratory System
Number the pictures in the respiratory system in order according to the path air takes
from when it enters the nasal passage to when it arrives in the lungs.
nasal passageways
pharynx
larynx
trachea
bronchi
bronchial tubes
alveoli
Activity Card 1
Activity Card PS 5.indd 1 8/29/13 3:34 PM
169
Cutout 4
Use on page 42 (Unit 1).
Cutout 5
Use on page 51 (Unit 1).
Cutouts
PSEC_5_SB_U6_P165-188.indd 169 16/1/19 16:01
• Science Lab
An experiment for students to put
their science research skills into
practice and gain practical knowledge
of the unit concepts.
• Test Study Page
A Summary and review of each
unit that students glue into their
notebooks.
Special Pages
Support Pages
• Cutouts
Images and texts to remove and glue in activities
throughout the book.
• Activity Cards
Separate cards in a handy envelope with
complementary experiments, activities and
materials.
Students can download the
material from the Santillana
Digital Platform.
Digital Lessons
8
PSEC_5_Teacher's Guide_P001-204.indd 8 1/29/19 09:39

9. Pathway to Science 5
Experimental Procedure
Which Variables Can You Control?
In an experiment, you need to determine what factors or variables might affect
the results. In this case, there are two variables: humidity is the independent
variable, and growth of fungi is the dependent variable. Which of the variables
do you think affects the experiment?
humidity fungi growth
What Supplies Do You Need?
For any experiment, you need supplies to create the correct conditions to
observe an event. In this experiment, you want to see if fungi will grow on food.
Here is a list of possible supplies.
Mark the supplies you think are necessary:
measuring tape piece of wood water lightbulb bread
bleach storage bag jar tongs
Plan and study independently
One or Two Storage Bags?
You need two storage bags to do this experiment. In the first bag, you will manipulate the independent variable (the
humidity). In the second, the independent variable will not change. The second bag is called the control group. A
control group is necessary to see if the manipulation of the independent variable really is what caused the results, and
not some indeterminate factor.
In an experiment, one variable
can be manipulated to observe
its effects. This is called the
independent variable. The
dependent variable changes as a
result of the manipulation of the
independent variable. The control
variables are not manipulated or
changed in anyway.
A science experiment is a scientific method used to verify a hypothesis. To
conduct a successful experiment, it is important to think about the variables,
the supplies and the process. Now we will do a science experiment to answer
this question: does humidity help fungi grow on food?
81
Life Science
U2 PSst5.indd 81 8/9/13 11:07 AM
Basic Framework
Fungi grow in humid places—for example, in the shade of trees in parks and gardens. These are places where sunlight
cannot reach. They prefer warm, wet places that provide the necessary nutrients, and even grow in decomposing food.
Observation
Marcus looked at the oranges on the ground
in his backyard. After it rained, fungi started
to grow on their peel. The oranges his mom
picked before it rained did not have any fungi.
Why did the oranges left outside grow fungi?
Research Question
How does humidity affect the growth of fungi?
Hypothesis
Mark the hypothesis you think is correct.
Humidity helps fungi grow.
Humidity does not help fungi grow.
Predictions
How will humidity affect the growth of fungi on food?
Where Fungi Grow
Science Lab
Scientific Skill: Experiment
Before the rain.
After the rain.
Humidity is the amount
of moisture in the air.
Word Focus
80 Unit 2
U2 PSst5.indd 80 8/9/13 11:06 AM
Formulate explanations by comparing your results with your
predictions
circuit 1 circuit 2
+
+
+
+
Predictions
1. Look at the diagrams of the following circuits.
a. What would happen if one of the lightbulbs in circuit 1 were disconnected? Would the other stay on?
b. What would happen if one of the lightbulbs in circuit 2 were disconnected? Would the other stay on?
Experimental Procedure
1. In groups of three, collect the following materials:
• 1 nine volt battery with connector
• 1 meter of electric cable
• 2 portable light sockets
• 2 six volt lightbulbs
• 1 switch
• 1 set of pliers
2. Put together circuit 1. Press the switch and observe what
happens.
3. Turn off the lights and take out one of the lightbulbs. Press
the switch again and observe what happens.
4. Then put together circuit 2. Press the switch and observe
what happens.
5. Turn off the lights, and take out one of the lightbulbs.
Press the switch again and observe what happens.
6. Record your observations in the Results section.
circuit 1
circuit 2
105
Physics and Chemistry
U3 PSst5.indd 105 7/10/13 4:10 PM
Basic Framework
In groups of three, write the basic framework for this activity.
Observation
Look at the following situation:
When a lightbulb burns out in your house, do the others keep working? Why or why not?
Research Question
What happens when a series circuit receptor is damaged? What if the same happens to a parallel circuit receptor?
Hypothesis
Mark the hypothesis you think is correct.
In a series circuit, if one of the receptors is damaged, the others stop working. In a parallel circuit, if one of
the receptors is damaged, the others continue working.
In a series circuit, if one of the receptors is damaged, the others continue working. In a parallel circuit, if one
of the receptors is damaged, the others stop working.
Series and Parallel Circuits
Science Lab
Scientific Skill: Compare predictions with results
dependable
The basic framework is the theory of an experiment. It should contain the scientific concepts
necessary to develop the experiment. To create a basic framework, find information in reliable sources,
like your textbook or other science books and journals. In this experiment, the important concepts are
series and parallel circuits.
104 Unit 3
U3 PSst5.indd 104 7/10/13 4:10 PM
Scientific Research Skills
Process Example
An Observation allows you to obtain information about
an object or event by using the five senses and scientific
instruments.
A boy observed that the trees by a river do not grow as large as
they get farther away from the river.
Research Questions come from the object or event that you
want to explain. The question should include dependent or
independent variables.
This observation made the boy ask:
– How does the location of the river influence the size of the trees?
A Hypothesis is an anticipated answer to your research
question, but it is not automatically true. You need to test
your hypothesis first in order to confirm or reject it.
The boy responded:
– The distance of the trees from the river is directly related to the
amount of water the trees receive.
Predictions are the expected results of your hypothesis.
He made two predictions:
– The trees that are closer to the river will have greener leaves
because they receive more water.
– The trees that are farther away from the river will have leaves that
are less green because they receive less water.
Experimental Procedure allows you to test your hypothesis
by doing an experiment. At this stage, you collect materials,
control variables and follow the step-by-step instructions to
correctly carry out the experiment.
To carry out the experiment, the child needed four plants of the
same size, a ruler and some water.
The controlled variable was the amount of water. He followed these
steps: label the plants and then water each one with a different
amount of water. Each day he measured the height of the plants.
Results are the data or information you obtain from an
experiment. You can record and represent them in many
different ways—for example, in tables or graphs.
The boy recorded the heights of the plants in a table and later
made a graph with the information.
Interpreting and Analyzing Results is the stage when you
explain your results, make connections between them and
find the answer to the research question.
Using his observations, he related the amount of water that the
plants receive to their growth.
Conclusions are the central ideas you learn from each
previous stage. At this stage, you should be able to confirm
or reject your hypothesis. The conclusions can give you new
research questions for future investigations.
He interpreted his data and concluded that the more water a plant
receives, the more it will grow. This explains why the trees by the
river are different sizes. The boy confirmed his hypothesis and
answered the research question.
What other questions can you think of to research?
Plan
and
Conduct
Research
Analyze
Evidence
and
Communicate
independent
variable
dependent
variable
Observe
and
Question
58 St Aldates
Oxford
OX1 1ST
United Kingdom
Pathway to Science Student’s Book Level 5
First Edition: 2014
ISBN: 978-607-06-0908-4
Pathway to Science 5 is a collaborative work, created and designed by
the Department of Educational Research of Santillana.
© Richmond Publishing, S.A. de C.V. 2014
Av. Río Mixcoac No. 272, Col. Acacias,
Del. Benito Juárez, C.P. 03240, México, D.F.
Publisher: Justine Piekarowicz
Editor: Dominic Wright
Art and Design Coordinator: Marisela Pérez
Pre-Press Coordinator: Daniel Santillán
Illustrations: Juan Esteban del Pino Briceño, Sergio Quijada Valdés,
Alejandro Rojas Contreras
Photographs: César Vargas Ulloa
© THINKSTOCK: pp. 62, 74, 75, 77 (iStockphoto);
PhotoObjects.net p. 61 (PhotoObjects.net)
2005 Volker Brinkmann p. 11, Salmonella typhimurium
2009 Louise Docker p. 13, Xylocopa aeratus
2011 Oxfam East Africa p. 74, Collecting water
2011 Deuterostome p. 13, Euglena viridis
2005 Rocky Mountain Laboratories/NIAID/NIH p. 13, Escherichia coli
2012 NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring p. 126, Earth
REPOSITORIO © Grupo Santillana
Cover Design: Erika Martínez
Cover Photograph: iStockphoto, Octopus eye
All rights reserved. No part of this work may be reproduced, stored in
a retrieval system or transmitted in any form or by any means without
prior written permission from the Publisher.
Richmond publications may contain links to third party websites or
apps. We have no control over the content of these websites or apps,
which may change frequently, and we are not responsible for the
content or the way it may be used with our materials. Teachers and
students are advised to exercise discretion when accessing the links.
The Publisher has made every effort to trace the owner of copyright
material; however, the Publisher will correct any involuntary omission at
the earliest opportunity.
First published by Santillana del Pacífico S.A. de Ediciones
Printed in Mexico by
portadilla PSst5.indd 2 9/11/13 1:05 PM
5
What happens to food after
I eat it?
One way to answer this question is to learn
how to use:
Scientific Research Skills
The development of these skills does not
require you to follow one method step
by step. Instead, they can be adapted to
each question you wish to answer.
These skills will help you explain
events that happen in our
surroundings.
The develo
plain
r
Let’s learn about scientific skills! These skills will
be applied in the experiments in your book. Soon you
will be able to answer your own questions about the
mysteries of the world around you.
mysteries of the world around you.
We will show you a new and fun way to learn
about science!
Student’s Book
Name
Glue your
picture here.
portadilla PSst5.indd 1 9/9/13 4:25 PM
The Digital Book is a digital version of the Student’s Book and it includes
audio recordings and extra resources. It is ready to be downloaded from
the Santillana Digital Platform.
Digital Book
The Scientific Research Skills Procedures develops
students’ knowledge of the scientific method and helps
them apply specific research skills in the classroom.
It also appears in the back of the Teacher’s Guide and
includes the following information:
• Research process
• Application through an example related to the
theme and grade level
• Stages of scientific research
Scientific Research Skills Procedures
Each stage of the experiment in the
Science Lab is shown in the same color as
it appears in the Scientific Research Skills
Procedures. The specific scientific skill that
students work on in each Science Lab is
explained during the experiment. Students
can also work with the Procedures to learn
more about the stages involved in scientific
research as they follow them
in the experiment.
Relationship between the Scientific Research
Skills Procedures and the Science Lab
9
58 St Aldates
Oxford
OX1 1ST
United Kingdom
Pathway to Science Student’s Book Level 5
First Edition in Ecuador: 2018
ISBN: 978-9942-31-168-9
Pathway to Science 5 is a collaborative work,
created and designed by the Department of
Educational Research of Santillana.
© Richmond Publishing, S.A. de C.V. 2014
Av. Río Mixcoac No. 274, Col. Acacias,
Del. Benito Juárez, C.P. 03240, México, D.F.
Publisher: Justine Piekarowicz
Editor: Dominic Wright, María del Carmen García
Art and Design Coordinator: Marisela Pérez
Pre-Press Coordinator: Daniel Santillán
Illustrations: Juan Esteban del Pino Briceño, Sergio
Quijada Valdés, Alejandro Rojas Contreras
Photographs: César Vargas Ulloa
©REPOSITORIO: Grupo Santillana;
©THINKSTOCK: Hemera p. 120 (Brett Mulcahy);
iStock pp. 62 (Jacek Chabraszewski), 74 (Elena
Stepanova), 75 (Blaj Gabriel), 77 (Natalia Klenova),
89 (Jeff_Hu), (Elena Schweitzer); PhotoObjects.net
p. 61 (PhotoObjects.net); p. 177 (Fuse)
2005 Volker Brinkmann p. 11, Salmonella
typhimurium
2009 Louise Docker p. 13, Xylocopa aeratus
2011 Oxfam East Africa p. 74, Collecting
water
2011 Deuterostome p. 13, Euglena viridis
2005 Rocky Mountain Laboratories/NIAID/NIH
p. 13, Escherichia coli
2012 NASA/NOAA/GSFC/Suomi NPP/VIIRS/
Norman Kuring p. 126, Earth
Cover Design: Erika Martínez
Cover Photograph: iStock, Octopus eye
All rights reserved. No part of this work may
be reproduced, stored in a retrieval system or
transmitted in any form or by any means without
prior written permission from the Publisher.
Richmond publications may contain links to third
party websites or apps. We have no control over
the content of these websites or apps, which may
change frequently, and we are not responsible for
the content or the way it may be used with our
materials. Teachers and students are advised to
exercise discretion when accessing the links.
The Publisher has made every effort to trace the
owner of copyright material; however, the Publisher
will correct any involuntary omission at the earliest
opportunity.
Printed in: Imprenta Mariscal
Scientific Research Skills
Process Example
An Observation allows you to obtain
information about an object or event
by using the five senses and scientific
instruments.
A boy observed that the trees by a
river do not grow as large as they get
farther away from the river.
Research Questions come from
the object or event that you want to
explain. The question should include
dependent or independent variables.
This observation made the boy ask:
– How does the location of the river
influence the size of the trees?
A Hypothesis is an anticipated
answer to your research question, but
it is not automatically true. You need
to test your hypothesis first in order to
confirm or reject it.
The boy responded:
– The distance of the trees from the ri-
ver is directly related to the amount
of water the trees receive.
Predictions are the expected results
of your hypothesis.
He made two predictions:
– The trees that are closer to the river
will have greener leaves because they
receive more water.
– The trees that are farther away from
the river will have leaves that are less
green because they receive less water.
Experimental Procedure allows you
to test your hypothesis by doing an
experiment. At this stage, you collect
materials, control variables and
follow the step-by-step instructions to
correctly carry out the experiment.
To carry out the experiment, the child
needed four plants of the same size, a
ruler and some water.
The controlled variable was the amou-
nt of water. He followed these steps:
label the plants and then water each
one with a different amount of water.
Each day he measured the height of
the plants.
Results are the data or information
you obtain from an experiment. You
can record and represent them in
many different ways—for example, in
tables or graphs.
The boy recorded the heights of the
plants in a table and later made a
graph with the information.
Interpreting and Analyzing Results
is the stage when you explain your
results, make connections between
them and find the answer to the
research question.
Using his observations, he related
the amount of water that the plants
receive to their growth.
Conclusions are the central ideas
you learn from each previous stage.
At this stage, you should be able to
confirm or reject your hypothesis.
The conclusions can give you new
research questions for future investi-
gations.
He interpreted his data and con-
cluded that the more water a plant
receives, the more it will grow. This
explains why the trees by the river are
different sizes. The boy confirmed his
hypothesis and answered the re-
search question.
What other questions can you think
of to research?
Observe
and
Question
Analyze
Evidence
and
Communicate
Plan
and
Conduct
an
Investigation
independent variable
dependent variable
PSEC_5_Teacher's Guide_P001-204.indd 9 1/29/19 09:39

10. Student’s Book Table of Contents
10
Unit Section 1 Section 2
Body Systems
Education through Values:
caring for the environment
The Levels of Biological Organization
– The Discovery of Cells
– Classifying Living Things
– The Cell
– Organs
– Systems
– Organisms
pg. 10
The Digestive System
– The Organs of the Digestive System
– The Digestive Process
– The Beginning of the Digestive Process
– Swallowing
– Peristaltic Movements
– Digestion in the Stomach: The Process Continues
– The End of the Digestive Process
– Absorption
– Elimination of Waste: The Final Process
pg. 18
Nutrition and
Health
Education through Values:
solidarity, promoting a
healthy lifestyle
Nutrition
– Food Gives Us Energy
– Food
– Components of Food
– Proteins
– Carbohydrates
– Lipids
– Vitamins and Minerals
– Nutritional Composition of Foods
– The Food Pyramid
pg. 58
Microorganisms
– Health and Illnesses
– Types of Illnesses
– Microorganisms: Bacteria, Fungi and Viruses
– Harmful Microorganisms
– Beneficial Effects of Microorganisms
– Taking Care of Your Body
pg. 70
Electricity
Education through Values:
respecting rules and caring
for the planet
Electric Energy
– Energy in Our Surroundings
– Renewable Energy Sources
– Changes in Electric Energy
– Electricity: The Important Scientists
pg. 88
Electric Circuits
– Electric Current
– Different Types of Electric Currents
– Electric Circuits
– Series Circuit
– Parallel Circuit
– Electric Circuits in Our Homes
pg. 96
The Hydrosphere
Education through Values:
protecting earth’s water
Water on Earth
– Land and Water
– The Hydrosphere
– Different Types of Water on Our Planet
– The Distribution of Water on Land
– The Water Cycle
– The Importance of Water for Living Things
pg. 126
Characteristics of Oceans, Seas and Lakes
– Differences between Fresh Water and Salt Water
– Types of Water in Oceans, Seas and Lakes
– Characteristics of Oceans and Seas
– Effects of Water Conditions on Living Things
– Ocean Zones and Diverse Forms of Life
– Lakes
– Living Things in Lakes
– Seas
– Ocean Currents
– Waves
pg. 136
1
2
pages
8–55
pages
56–85
3
pages
86–123
4
pages
124–157
Unit Section 1 Section 2 Section 3
Body Systems
Education through
Values:
caring for the
environment
The Levels of Biological
Organization
– The Discovery of Cells
– Classifying Living Things
– The Cell
– Organs
– Systems
– Organisms
pg. 10
The Digestive System
– The Organs of the Digestive System
– The Digestive Process
– The Beginning of the Digestive Process
– Swallowing
– Peristaltic Movements
– Digestion in the Stomach: The Process
Continues
– The End of the Digestive Process
– Absorption
– Elimination of Waste: The Final Process
pg. 18
The Circulatory System
– Understanding the Circulatory System
– Circulatory System Components
– Our Blood
– Components of Blood
– Blood Vessels
– Types of Blood Vessels
– The Heart’s Function
pg. 34
Nutrition and
Health
Education through
Values:
solidarity, promoting
a healthy lifestyle
Nutrition
– Food Gives Us Energy
– Food
– Components of Food
– Proteins
– Carbohydrates
– Lipids
– Vitamins and Minerals
– Nutritional Composition of Foods
– The Food Pyramid
pg. 58
Microorganisms
– Health and Illnesses
– Types of Illnesses
– Microorganisms: Bacteria, Fungi and
Viruses
– Harmful Microorganisms
– Beneficial Effects of Microorganisms
– Taking Care of Your Body
pg. 70
Electricity
Education through
Values:
respecting rules and
caring for the planet
Electric Energy
– Energy in Our Surroundings
– Renewable Energy Sources
– Changes in Electric Energy
– Electricity: The Important Scientists
pg. 88
Electric Circuits
– Electric Current
– Different Types of Electric Currents
– Electric Circuits
– Series Circuit
– Parallel Circuit
– Electric Circuits in Our Homes
pg. 96
Conductors and Insulators
– Conductors and Insulators of Electricity
– Conductors
– Insulators
–
Components of a Circuit: Conductors
and Insulators
– Daily Uses of Conductors and
Insulators
– Safe Ways to use Electric Devices
pg. 110
The
Hydrosphere
Education through
Values:
protecting earth’s
water
Water on Earth
– Land and Water
– The Hydrosphere
– Different Types of Water on Our Planet
– The Distribution of Water on Land
– The Water Cycle
– The Importance of Water for Living
Things
pg. 126
Characteristics of Oceans, Seas
and Lakes
– Differences
between Fresh
Water and Salt
Water
– Types of Water
in Oceans, Seas
and Lakes
– Characteristics
of Oceans and
Seas
– Effects of Water
Conditions on
Living Things
– Ocean Zones
and Diverse
Forms of Life
– Lakes
– Living Things in
Lakes
– Seas
– Ocean Currents
– Waves
pg. 136
1
2
pages
8–55
pages
56–85
3
pages
86–123
4
Glossary
pages 158–164
Cutouts
pages 165–185
pages
124–157
PSEC_5_Teacher's Guide_P001-204.indd 10 1/29/19 09:39

11. Pathway to Science 5
11
Section 3 Section 4 Science Lab Evaluations Summary and Review
The Circulatory System
– Understanding the Circulatory System
– Circulatory System Components
– Our Blood
– Components of Blood
– Blood Vessels
– Types of Blood Vessels
– The Heart’s Function
pg. 34
The Respiratory System
– Respiration
– Organs of the Respiratory
System
– The Role of Respiratory
System Organs
– Understanding Respiration
pg. 44
The Function
of Saliva
pg. 28
What Do You Know?
Initial Evaluation
pg. 9
Let’s Check!
Intermediate Evaluation
pg. 32
What Did You Learn?
Final Evaluation
pg. 52
Test 1 Study Page
Where Fungi
Grow
pg. 80
What Do You Know?
Initial Evaluation
pg. 57
Let’s Check!
Intermediate Evaluation
pg. 68
What Did You Learn?
Final Evaluation
pg. 84
Test 2 Study Page
Conductors and Insulators
– Conductors and Insulators of Electricity
– Conductors
– Insulators
– Components of a Circuit: Conductors and
Insulators
– Daily Uses of Conductors and Insulators
– Safe Ways to use Electric Devices
pg. 110
Series and
Parallel
Circuits
pg. 104
What Do You Know?
Initial Evaluation
pg. 87
Let’s Check!
Intermediate Evaluation
pg. 108
What Did You Learn?
Final Evaluation
pg. 120
Test 3 Study Page
The Effects
of Water
Pollution on
Living Things
pg. 150
What Do You Know?
Initial Evaluation
pg. 125
Let’s Check!
Intermediate Evaluation
pg. 148
What Did You Learn?
Final Evaluation
pg. 154
Test 4 Study Page
Glossary
pages 158–164
Cutouts
pages 165–185
Section 4 Science Lab Evaluations Summary and Review Digital Section
The Respiratory
System
– Respiration
–
Organs of the
Respiratory System
–
The Role of Respiratory
System Organs
– Understanding
Respiration
pg. 44
The Function
of Saliva
pg. 28
What Do You
Know? Initial
Evaluation
pg. 9
Let’s Check!
Intermediate Evaluation
pg. 32
What Did You
Learn? Final
Evaluation
pg. 52
Test 1 Study Page Time to teach: After page 43
Digital Lesson 1. Structure and function
of sense organs
Digital Lesson 2. Illnesses, prevention
and care of body systems
Digital Lesson 3. Traditional medicine
Digital Lesson 4. Female and male
reproductive systems
Digital Lesson 5. Changes in puberty
Where Fungi
Grow
pg. 80
What Do You
Know? Initial
Evaluation
pg. 57
Let’s Check!
Intermediate Evaluation
pg. 68
What Did You
Learn? Final
Evaluation
pg. 84
Test 2 Study Page Time to teach: After page 67
Digital Lesson 6. Eating disorders:
bulimia and anorexia
Time to teach: After page 78
Digital Lesson 7. Healthy habits in puberty
Digital Lesson 8. Biological, psychological
and social aspects of sexuality
Series and
Parallel
Circuits
pg. 104
What Do You
Know? Initial
Evaluation
pg. 87
Let’s Check!
Intermediate Evaluation
pg. 108
What Did You
Learn? Final
Evaluation
pg. 120
Test 3 Study Page Time to teach: After page 116
Digital Lesson 9. The impact
of hydroelectric plants
The Effects
of Water
Pollution on
Living Things
pg. 150
What Do You
Know? Initial
Evaluation
pg. 125
Let’s Check!
Intermediate Evaluation
pg. 148
What Did You
Learn? Final
Evaluation
pg. 154
Test 4 Study Page
PSEC_5_Teacher's Guide_P001-204.indd 11 1/29/19 09:39

12. The illustration could lead students to think that
the organs shown are the only organs in the human
body. Tell them that apart from what is shown, other
organs also exist, such as bones and muscles, which
give shape and support to the human body and
allow movement.
Possible Difficulties
nouns: absorption, artery, biology,
blood, bolus, bowel, capillary,
carbohydrate, cell, chemistry,
circulation, clot, digestion,
digestive system, egestion, fat,
function, gland, heart, ingestion,
kidney, large intestine, lipid,
lungs, microorganism, mineral,
muscle, nervous system, nutrient,
organ, organism, organization,
oxygen, photosynthesis, plasma,
protein, pulse, respiration,
secretion, small intestine,
sphincter, stomach, system,
tissue, vein, vitamin
verbs: beat, breathe, circulate,
contract, convert, digest, enter,
exit, flow, growl, pump, secrete,
shake, spread, store, survive
adjectives: antiseptic,
circulatory, digestive, involuntary,
multicellular, peristaltic,
pulmonary, respiratory, unicellular,
vital, voluntary
Unit Vocabulary
Materials: poster paper
Direct students’ attention to the
illustration of the man on page
8. Get them to name the organs
and other things depicted. Even if
students cannot yet name them,
have volunteers who can draw well
draw an approximation of the man
and his organs on poster paper.
Display it and have students come
up and label the man with new
vocabulary during every relevant
lesson of the unit so that he is
fully labeled and can be used as a
reference by the end.
Setting Off
Unit 1
1
Unit
Body
Systems
In this unit you will learn to:
• describe the levels of biological organization.
• identify the basic structures and functions of the digestive system.
• identify the basic structures and functions of the circulatory system.
• identify the basic structures of the respiratory system and explain respiration.
• make predictions in an independent research experiment.
8
chest
Key Words
cell
function
system
convert
circulate
Unit 1
12 Unit 1
heart
lungs
stomach
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13. Life Science
What Do You Know? Initial Evaluation
Go to Cutout 1 on page 165. Glue the names of the organs in the correct boxes.
1. Mark the function of each organ listed with a .
Scientific Skill: Predict
2. A scientist observes the following in a lab:
a. Circle the difference between the digestive tracts of the mice.
b. What are the possible side effects of an irregular digestive tract? (Situation 2)
Heart Lungs Stomach
Allow air to enter and exit
the body
Pumps blood to other parts
of the body
Helps digest food
9
Situation 1 Situation 2
The mouse has a normal digestive tract. The mouse has an irregular digestive tract.
Life Science
For this activity, students use
their prior knowledge to relate the
characteristics of living beings
and the functions of some organs
of the human body.
Initial Evaluation
All predictions made to answer the
scientific skill question should be
considered correct. However, it is
important to evaluate which organ
they mark in the mouse’s digestive
system and the prediction they
make in regard to the side effects
of this irregularity.
Initial Evaluation:
Scientific Skill
The Human Body (www.tinybop.
com): This app allows students
to explore a working model of the
body. Every part is animated and
interactive: the heart beats, guts
gurgle, lungs breathe, the skin
feels and eyes see.
This is my body - Anatomy for
kids (www.urbn-pockets.com):
Created by a team of medical
doctors, educators and parents,
this app features information
about all important aspects of
the human body, including the
digestive system, respiratory
system, circulatory system,
musculoskeletal system and
nervous system.
Recommended Apps
13
Answer Key and Teaching Notes Pathway to Science 5
Life Science
Notes
The mouse cannot digest in a normal way because it has no stomach. This would have
serious consequences for how the mouse digests food.
PSEC_5_Teacher's Guide_P001-204.indd 13 1/29/19 09:39

14. When asked to identify
similarities, students may limit
themselves to only what they see
in the image. Ask them about the
characteristics of the dog and the
plant, how they feed, what they
need to grow, and so on, until the
question of what they are made of
comes up. This will help introduce
the concept of cells.
Possible Difficulties
Grammar prefixes: micro-
Vocabulary nouns: atom, bacteria,
biology, cell, chemistry, cork,
ecology, feeding, growth, level,
macromolecule, microorganism,
microscope, organization,
reproduction
verbs: prove
adjectives: complex, multicellular,
unicellular
Skill Students can identify and
define prefixes
Language Focus
demonstrated
The Discovery of Cells
Think about the smallest object visible to the naked eye. Thanks to the microscope,
we can now see objects that we could not see before. Robert Hooke, an
English scientist, invented the microscope in the 17th century. He used his
invention to look closely at thin slices of cork.
Based on his observations, Hooke drew the pieces of cork he saw. He
showed they consisted of smaller parts that he named cells. After many
years, it was proven that cells are present in all living things.
Classifying Living Things
Look at the images and identify similarities between the two organisms.
Do they have anything in common? It does not look like it, but they are actually
very similar. Even if we cannot see it, organized cells form both organisms. Cells
group together and create more complex parts. For example, cells form the
bones and muscles of animals, and the leaves and stems of plants.
We can see that living things are created in a specific way: from small to big and
from simple to complex. In other words, living things have levels of organization
that go from the cell to the entire organism.
Drawing of Hooke’s observations.
spongy bark of a tree
Connecting
Section
1 The Levels of Biological Organization
1
The levels of biological
organization are studied
by different areas:
• chemistry: atoms to
macromolecules.
• biology: cells to
organisms.
• ecology: organisms
and the environment.
Did You Know...?
Unit 1
10
T
T
w
s
y
UNIT 1: BODY SYSTEMS
Section 1: The Levels of Biological
Organization
• The Discovery of Cells
• Classifying Living Things
• The Cell
• Organs
• Systems
• Organisms
Section Organization
14 Unit 1
PSEC_5_Teacher's Guide_P001-204.indd 14 1/29/19 09:39

15. It may be difficult for students to
understand the concept of cells,
given that it is abstract without
a microscope. Show images of
different types of cells from organs
of the body. This way, students
can visualize and become familiar
with them and see that there are
different types of cells that are
specialized according to their
function.
Possible Difficulties
The concept of unicellular
organisms may generate a
perception that they are simpler
organisms. However, it is
important to highlight that they
are organisms that have different
mechanisms and specialized
structures to complete all their
vital processes.
Possible Difficulties
Call on a student to read the
information in the Challenge box
aloud. Have students guess what
micro- means. On the board, write
anti–, dis–, in–, mis–, pre–, re–
and un–. Form groups and ask
them to write the meaning of each
prefix and at least two examples
for each one.
Language Extension
the act of eating food
The Cell
Every living thing on the planet is different, and there is a great variety of plants
and animals. However, they all have one thing in common: they consist of cells.
The cell is the first and smallest level of biological organization. Although it is
a small structure, it is complex. The existence of life depends on the components
of the cell working together. In the following image, you can see a cell from the
nervous system.
Single-celled Organisms
Living things come in different shapes and sizes and have a different number of
cells. Some organisms consist of many cells (multicellular) and are easily visible.
Others consist of one cell (unicellular). Without a microscope, most unicellular
organisms are invisible. We call them microorganisms. In microorganisms, life
processes like feeding, growth and reproduction all occur in one cell.
Here you can see some unicellular
organisms. They are part of the first level
of the biological system.
Cells that form part of the nervous
system are called neurons.
bacteria bacteria protozoa
Describe the levels of biological organization
It is estimated that a human
has 75,000,000,000,000 (75
trillion) cells.
Did You Know...?
Microscopeandmicroorganism
both start with micro. What
do you think micro means?
Challenge
Life Science 11
15
Answer Key and Teaching Notes Pathway to Science 5
Life Science
Notes
PSEC_5_Teacher's Guide_P001-204.indd 15 1/29/19 09:39

16. While looking at the images,
students may think that all the
cells of an organism are the
same as the ones shown in the
image. To avoid this mistake, ask
questions such as: Are all the cells
in our body the same? Are they
the same size? Explain that cells
are different shapes and sizes,
depending on the function they
serve.
Common Mistakes
Vocabulary nouns: muscle, nerve,
organ, shape, size, system, tissue
verbs: communicate, form, survive
Skill Students can research and
present different types of cells
Language Focus
continue to exist
The Organization of Multicellular Organisms
The cell is the first level of biological organization. Unicellular organisms consist
of just one cell and never grow more than that. Think about your body. How
many cells do you think you have? Multicellular beings, like humans, have
millions of cells that unite and organize to form tissues, organs and systems.
These join to form a whole organism. Below you can see the different levels of
biological organization.
Tissue
Your body has millions of cells, but they cannot survive alone, so they form tissue.
Tissue is the second level of biological organization. It consists of a group of
cells that are similar in shape and size. They communicate to complete a certain
function. Each type of cell forms different tissue and has unique functions.
In the image, you can see an example of human tissue. Muscle tissue, consisting
of muscle cells, contracts and relaxes to move different parts of the body.
Tissue is an example of the second level
of biological organization. What types of
organisms have tissue?
Level 1
Cell
Level 2
Tissue
Level 3
Organ
Level 4
System
Level 5
Organism
Section 1 / The Levels of Biological Organization
Human beings are organized from small,
simple cells to complex systems. Is it possible
to find organs in unicellular beings?
Challenge
Unit 1
12
16 Unit 1
PSEC_5_Teacher's Guide_P001-204.indd 16 1/29/19 09:39

17. Emphasize that the cells in
the image in activity 2 are
not separated but joined
together. This will help them reach
the correct answer more easily.
Possible Difficulties
On the board, write: nerve cells.
Call on volunteers to come to the
board and write as many other
types of body cells as they can
think of: skin, brain, muscle,
blood. Form pairs. Have them
choose one of the cell types and
research it in a library or on the
Internet. They should be able
to report to the class the basic
function of the cell.
Language Extension
1. Write a U in the boxes next to unicellular organisms and an M next to the multicellular ones. Identify
2. Jonathan looks at this sample in his laboratory and confirms that it is tissue.
a. Why does Jonathan classify this as tissue? Explain
In nature, some living things consist of one cell (unicellular organisms), and others consist of
many cells (multicellular organisms).
Multicellular organisms possess millions of cells. Cells come together to form increasingly
complex structures: tissues, organs, systems and finally organisms.
Tissue is the second level of biological organization and consists of groups of cells that have
the same function. Examples are muscle tissue and nerve tissue.
Summarizing
Practicing
Describe the levels of biological organization
Life Science 13
17
Answer Key and Teaching Notes Pathway to Science 5
Life Science
Notes
Because he observed it under a microscope and saw
organized cells, which is a characteristic of tissue.
U M M
U
PSEC_5_Teacher's Guide_P001-204.indd 17 1/29/19 09:39

18. Students may tend to think that
organs are only found in animals.
To avoid this mistake, use a
plant’s leaf as an example and
invite students to analyze the
leaf’s composition. In a leaf’s
tissue, various tissues work as
a group and form organs with
specific functions.
Common Mistakes
Highlight the importance of
taking care of our organs. They
must function perfectly to keep
our organism healthy. Motivate
students to play sports and eat a
balanced diet that contributes to a
good state of health.
A Healthy Lifestyle
Vocabulary nouns: brain, carbon
dioxide, cornea, epidermis, hair,
heart, integumentary system,
iris, kidney, lens, mesophyll,
nails, nervous system, neuron,
photosynthesis, retina, skin,
spinal cord, surroundings
verbs: adjust, control, perform
Skill Students can describe the
functions of organs
Language Focus
everything around you
execute
organs that clean the blood
Section 1 / The Levels of Biological Organization
epidermis
mesophyll
lens
retina
iris
The eye is an organ. It represents the
third level of biological organization.
What other examples of this level can
you think of?
Groups of tissues work together to perform the
same function. They form organs, like this leaf.
cornea
Organs
Have you ever heard of the lungs, kidneys or the heart? These are all examples
of organs: the third level of biological organization. An organ consists of various
groups of tissues working together to complete the same function. For example,
in plants, leaves are the organs responsible for photosynthesis. Leaves consist
of two types of tissues: the epidermis and the mesophyll.
Animal organs are more complex than plant organs. For example,
think of our eyes. They allow us to see light and our surroundings.
To perform this function, the eye has many types of tissues
and structures that work together to allow us to see.
The following image shows the structure of the eye.
Pay attention to the different tissues.
Connecting
Photosynthesis is the
process by which plants
produce food using
carbon dioxide, water
and sunlight.
Word Focus
Unit 1
14
18 Unit 1
PSEC_5_Teacher's Guide_P001-204.indd 18 1/29/19 09:39

19. Tell students that scientists first
thought that the nervous system
was not formed by cells like the
other systems, but there was little
information to support or reject the
idea. Over the years, microscopic
techniques were perfected that
finally showed that the nervous
system was also formed by cells
called neurons.
In 5 Minutes
In the Practicing activity, the
structure of muscles might
confuse students because they
may think of specific muscles,
such as the biceps or deltoids.
However, the table asks for the
level of biological organization
that refers to all muscle tissue.
Possible Difficulties
Form two teams. Call a student
from each team to the front of the
room. A student from one team
must name an organ. The other
student must say the organ’s
function to score two points. If he/
she cannot, the rest of the team
gets an opportunity to say the
function for one point. Teams take
turns naming organs. You can
expand the game to name systems
as well.
Language Extension
Describe the levels of biological organization
1. Complete the table with the correct level of biological organization.
Compare and Contrast
Organs are the third level of biological organization. They are groups of tissues that work together.
Systems are the fourth level of biological organization. They are groups of organs that work together.
Summarizing
The nervous system is an example
of the fourth level of biological
organization. It is a group of organs
that allow us to control our senses
and other organs and systems.
spinal cord
Structure Neuron Muscle Brain Nervous System Leaves
Level
brain
Systems
The fourth level of biological organization
is a system. A system is a group of
organs that work together to perform
the same function.
Forexample,thenervoussystemconsists
of two principal organs: the brain and
the spinal cord. The two organs work
together to control other organs and
to adjust to the environment.
Practicing
Some structures, like skin,
hair and nails, form part of
theintegumentarysystem.
This system helps protect
our bodies.
Did You Know...?
Life Science 15
19
Answer Key and Teaching Notes Pathway to Science 5
Life Science
Notes
First level Second level Third level Fourth level Third level
PSEC_5_Teacher's Guide_P001-204.indd 19 1/29/19 09:39

20. Tell students that of all the levels
of biological organization, the
organism is the most complex.
Highlight the idea that each level
of organization has characteristics
more complex than the previous
level. In this way, the circulatory
system, for example, can circulate
blood throughout the entire
organism. The heart, however,
an organ that forms part of this
system, cannot complete this
function alone.
Clarifying Concepts
Vocabulary nouns: bone, digestive
system, grasshopper, organism,
palm tree, skeletal system, tiger,
turtle
Skill Students can label and
present a multilevel diagram of an
organism
Language Focus Section 1 / The Levels of Biological Organization
Organisms
Look at the following images.
The living things above are all multicellular organisms. At what level of biological
organization do you classify them? You will notice that they are different from the
previous levels. This is because they are all part of the fifth and final level: the
organism.
A multicellular organism consists of several biological systems that work together
to allow its body to function. A cat is an organism that has a digestive system, a
nervous system and a skeletal system, among others. They all help the cat move
and live.
Cats are multicellular
organisms that have all
five levels of biological
organization, from single
cells to a complete organism.
In this image, you can see
all five levels in relation to
the skeletal system.
Level 1
Bone Cell
Level 2
Bone Tissue
Level 3
Bone
Level 4
Skeletal System
Level 5
Cat
tiger
tree
turtle
grasshopper
palm tree
Connecting
Cats and other animals
have a skeletal system.
What is the equivalent
structure in a tree?
Challenge
Unit 1
16
20 Unit 1
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21. Form the same pairs from the
Language Extension activity on
page 15 of the Teacher’s Guide
and have them draw a five-level
diagram of an organism of their
choice, similar to the one on
page 16 of the Student’s Book
and based on the cells that they
researched. They might also refer
to the five-level diagram on page
12 of the Student’s Book. Make
sure students label each level
of the diagram and name any
applicable organs visible in level
4. Students may present and
display their diagrams.
Language Extension
Quiz Yourself
Describe the levels of biological organization
1. Number the levels 1–5 from least complex to most complex. Put in order
2. Which level of biological organization includes all the other levels? Explain
tissue organism cell organ system
1. Complete the following chart.
Multicellular organisms are the fifth level of biological organization. They
are living things with many biological systems that help them live and move.
Summarizing
Practicing
The Basic Levels of Biological Organization
Level Description Examples
Cell
Group of cells that work together.
heart, lungs
System
lion, lizard
Life Science 17
21
Answer Key and Teaching Notes Pathway to Science 5
Life Science
Notes
The fifth level, since an organism consists of systems, organs, tissues
and cells.
2 5 1 3 4
Basic unit that forms all living things. neurons
Tissue muscle tissue, skin
Organ Group of tissues that work together.
Group of organs that work together. respiratory system
Organism Individual made up of different systems.
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22. Tell students that the digestive
glands are mentioned apart from
the digestive tract because their
function is to secrete substances
that assist in the digestion of food.
Clarifying Concepts
Vocabulary nouns: absorption,
anus, bile, carbohydrate,
digestion, digestive process,
digestive tract, egestion,
esophagus, fat, gastric acid,
gland, ingestion, large intestine,
lipid, liver, mineral, mouth,
nutrient, pancreas, pancreatic
acid, protein, salivary gland, small
intestine, stomach, vitamin, waste
verbs: convert, eliminate, produce,
secrete, swallow
Skill Students can categorize and
rank foods according to nutritional
parameters
Language Focus
pass from the mouth
to the stomach
Pancreas: produces
pancreatic acid.
Salivary Glands:
produce saliva.
Liver: produces bile.
Mouth: the opening of the
digestive tract.
Esophagus: a tube that
is about 30 centimeters
long and connects the
mouth to the stomach.
Stomach: a muscular organ
that produces gastric acid.
Small Intestine: a six-
meter-long tunnel that
connects to the stomach.
It absorbs nutrients.
Large Intestine: the last part
of the digestive system, which
eliminates waste.
The digestive system consists of the
digestive tract and digestive glands. Its
purpose is to convert food into nutrients,
which give us energy.
Look at the following image of the digestive system.
Pay attention to all the organs.
The Organs of the Digestive System
produce and
emit
Have you ever wondered what happens to food after you
swallow it? Where does it go? How is it used? The answers
to these questions are related to one of the systems in
our bodies: the digestive system. This system consists
of a group of organs that convert food into nutrients and
eliminate what we do not need.
The digestive organs surround the digestive tract, which
starts at the mouth and ends at the anus. This system
also includes a group of digestive glands. The glands
secrete various substances that convert food into nutrients.
Nutrients give our bodies the energy we need to live.
Connecting
Section
2 The Digestive System
Unit 1
18
T
s
s
t
o
o
e
UNIT 1: BODY SYSTEMS
Section 2: The Digestive System
• The Organs of the Digestive System
• The Digestive Process
• The Beginning of the Digestive Process
• Swallowing
• Peristaltic Movements
• Digestion in the Stomach: The Process
Continues
• The End of the Digestive Process
• Absorption
• Elimination of Waste: The Final Process
Section Organization
22 Unit 1
CN.3.2.3. To describe, with the support of models, the structure and function of the digestive system.
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23. Tell students about William
Beaumont, a North American
doctor as well as a pioneer in
describing the digestive process.
He was able to do his research
because his assistant was shot
in the stomach and the bullet left
a permanent hole. This allowed
Beaumont to observe what
happened inside his assistant’s
body while he ate.
In 5 Minutes
It is important to emphasize that
food has a mixture of nutrients,
and therefore digestion works
to transform food into nutrients
that can be used by our cells, the
most basic level of organisms. In
this way, we obtain the energy to
perform all our body’s functions.
Clarifying Concepts
Form groups. Give them a minute
or two to write as many foods
as they can think of that are
good sources of carbohydrates.
Then have them write their
answers on the board to share
them with the class. When all
groups have written their ideas,
the class can discuss and rank
the five healthiest sources of
carbohydrates. The task can be
repeated using protein or fat as
well.
Language Extension
The Digestive Process
Our digestive system converts food into simpler substances called nutrients,
which enter our cells and give us the energy we need to live. This process, called
the digestive process, consists of four stages, which occur in the following order:
• ingestion: when food enters the mouth
• digestion: the transformation of food in the digestive tract
• absorption: when nutrients enter the blood
• egestion: the elimination of waste through the anus
1. Label each organ of the digestive system. Identify
2. Put the stages of the digestion process in order. Sequence
egestion – digestion – ingestion – absorption
The digestive system allows the body to absorb nutrients and eliminate waste. The
stages of the digestive process are: ingestion, digestion, absorption and egestion.
Summarizing
Practicing
Identify the basic structures and functions of the digestive system
Nutrients are components of food
that give energy to an organism.
They also help regulate and repair
the body. Nutrients are classified
as: carbohydrates, found in foods
like bread; proteins, found in foods
like eggs; lipids and fat, found in
oils; and vitamins and minerals,
found in fruits and vegetables.
Did You Know...?
Life Science 19
23
Answer Key and Teaching Notes Pathway to Science 5
Life Science
Notes
mouth
liver
large intestine
esophagus
stomach
small intestine
ingestion digestion absorption egestion
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24. Students commonly think that
only the stomach is in charge of
digestion. To disprove this idea,
remind them of the concept of
digestion as the transformation
of food. Motivate students to
remember what food looks like
before we ingest it and the form
it takes when we chew it. Then
ask them about the changes that
happen.
Common Mistakes
Talk to students about parotitis,
or the mumps, a viral infection
that affects the salivary glands
and can cause fertility problems.
The infection is spread through
respiratory secretions and causes
the parotid gland (part of the
salivary glands) to swell.
In 5 Minutes
Vocabulary nouns: bolus,
carnivore, diameter, herbivore,
peristaltic movement, saliva,
teeth, tongue
verbs: chew, contract, rip
adjectives: straight
Skill Students can memorize organ
names and functions
Language Focus
bite repeatedly
with the teeth
The Beginning of the Digestive Process
As you already know, the digestive process consists of four stages: ingestion,
digestion, absorption and egestion.
Ingestion is the first stage, and it begins the moment you start to eat.
Put a piece of bread in your mouth, but do not chew. Wait one minute,
and then chew and swallow it. Did you notice any change in the food?
This is because digestion begins in the mouth. Teeth are used to chew
food and break it down into smaller pieces. Salivary glands in the mouth
produce saliva. The tongue moves and mixes the food with the saliva. All
these processes make a bolus, a ball of food ready to be swallowed and to
continue down the digestive tract.
Section 2 / The Digestive System
The mouth, teeth, tongue and saliva all
work together to convert food. Why can’t
babies eat solid food?
salivary
glands
teeth
tongue
Connecting
Each animal’s teeth are
adapted to the type of
food it eats. A carnivore
has long, sharp teeth to
rip meat, while herbivores
have large, flat teeth to
chew plants.
Remember!
Unit 1
20
24 Unit 1
CN.3.2.3. To describe with the support of models the structure and function of the digestive system and promote
its care.
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25. To emphasize the concept of
swallowing as an involuntary
process, discuss with students
that it is common for people to
accidentally swallow their chewing
gum as sometimes we do not
control the ingestion of food.
In 5 Minutes
Some students may find activity 1
of the Practicing section difficult
to understand. The activity’s
purpose is to show the swallowing
process and its peristaltic
movements in a practical way.
Be sure to explain that the ball
represents the food bolus, so
students can relate swallowing
with the materials in the activity.
Possible Difficulties
Materials: index cards, colored
pencils
Form pairs. Distribute several
index cards to each pair. Tell
students to draw one of the
organs of the digestive system
on each index card and color it.
They should take turns using the
index cards to quiz each other on
the names and functions of the
organs. The collection may be
added to as students study more
systems and organs. They can also
write the name and function of
each organ on the back of its card.
Language Extension
without curves
1. Put a small ball inside a tube that has the same diameter as the
ball. Use your fingers to squeeze the tube and push the ball to
the other side. If the ball represents the bolus, what does the
tube represent? What movement are you demonstrating with
your hands? Explain. Interpret
Ingestion is the first step of the digestive process. Digestion begins
in the mouth when food is converted into a bolus and pushed down
the esophagus. Peristaltic movements move the food through the
different organs of the digestive system.
Identify the basic structures and functions of the digestive system
Swallowing is a mechanism that allows
food to enter our bodies. After the food
is swallowed, peristaltic movements help
push the food through the digestive tract.
bolus
esophagus
Summarizing
becomes smaller
Swallowing
Take a sip of water. Did you notice what happens in the back of
your mouth? The process of moving liquid from the mouth to the
stomach is called swallowing. Swallowing consists of two stages.
The first stage is voluntary and occurs when we push food to the
back of the mouth. The second stage is involuntary and occurs
when the food enters the digestive tract and moves down the
esophagus to the stomach.
Peristaltic Movements
We have talked about food moving through the digestive tract.
How does this happen? The esophagus expands and contracts
to push the bolus down to the stomach. These movements are
called peristaltic movements.
Practicing
Diameter is the length of a
straight line passing through
the center of something
from one side to the other. In
this case, it is the thickness
of the tube.
Word Focus
Life Science 21
25
Answer Key and Teaching Notes Pathway to Science 5
Life Science
Notes
The tube represents the esophagus and the ball
is the food bolus. The finger movements are the
peristaltic movements that the esophagus makes to
move the food bolus.
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26. To facilitate understanding
of the role the stomach plays
in digestion, do the following
experiment: Empty a cup of jelly
into a plastic bag, making sure
that it does not lose its shape.
Pour in some water and gently
shake the bag. Explain that the
bag is the stomach, the jelly is
the food bolus, and the water is
the gastric juice that this organ
produces and mixes with the food
bolus, allowing its digestion.
Possible Difficulties
Talk to students about the
relationship between stomach
acidity and the ingestion of
certain foods. Explain that
the excessive consumption of
some foods, like spices, alters
the functioning of the cardiac
sphincter, which causes gastric
juices to irritate the stomach and
damage the esophagus. It can
also provoke major problems like
ulcers.
A Healthy Lifestyle
Vocabulary nouns: cardiac
sphincter, chyle, chyme, gastric
juice, intestinal juice, pancreas,
pancreatic juice, pylorus
sphincter, valve
verbs: growl, process
Skill Students can identify words
and pronunciations of Greek origin
Language Focus
The stomach is a very
important part of the
digestive system. Its
movements and gastric
juices help convert food
into nutrients.
bolus
gastric juices
stomach
esophagus
cardiac sphincter
chyme
small intestine
Section 2 / The Digestive System
Digestion in the Stomach: The Process Continues
Does your stomach ever make noises after you eat? Or have you ever heard your
stomach growling when you are hungry? This happens because the stomach is
a muscular organ shaped like a bean, with walls that move to help process food.
The bolus of food moves through the esophagus to reach the stomach. Then
it goes through a valve located at the entrance of the stomach. This valve is
called the cardiac sphincter. Its function is to allow food to pass through to the
stomach and to prevent stomach contents from entering the esophagus.
When food gets to the stomach, it mixes with
gastric juices. Gastric juices help with digestion
—the transformation of food into nutrients. For
example, proteins are digested in this process.
Gastric juices and peristaltic movements convert
the bolus into a thick liquid called chyme. This
liquid then moves toward the small intestine.
Connecting
• The word growl
normally describes
thesoundadogmakes
whenitisangry.Growl
also means the noise
your stomach makes
whenyouarehungry!
• A sphincter is a ring-
shaped muscle that
regulates the passage
of substances from
one place to the next.
Word Focus
It is important not to eat too much of
certain foods like chocolate or spices.
Some foods can have negative effects on
the cardiac sphincter, pushing food and
gastric juices back into the esophagus.
Staying Healthy
Unit 1
22
26 Unit 1
CN.3.2.3. To describe, with the support of models, the structure and function of the digestive system.
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