This document discusses population density and carrying capacity. It defines population density as the number of individuals per unit area and provides examples of calculating population density. An activity is described where students measure the area of a garbage bag and determine how many people can fit on it at different levels of folding to understand the concept of density. The document then introduces carrying capacity as the maximum population size an environment can sustain indefinitely. Limiting factors that influence human population growth such as water, food, living space, pollution and disease are identified. The ecological footprint is presented as a measure of human impact, with an example that if everyone lived as the average North American, we would need 3.8 Earths to support the global population.

1. How dense is your population?
8SCIENCE: Tues. Oct. 26

2. Population density
REVIEW: What are the characteristics of a
population? (3)
– Population Size
– Population Spacing
– Population Density
- What is population density?
- Number of individual organisms living in a certain
area

3. Population density examples
• # individuals = population density
area
1) If 2500 grasshoppers live in an area of 1 km², what is
the population density?
– 2500 grasshoppers/km²
2) If there are 23 students in our class, and the area of
this room is 46km², what is the population density?
– 2 students/km²
3) If 15 cows live in an area of 60km², what is the
population density?
– 4 cows/km²

4. Population density activity:
Quick activity: your group will be given a garbage bag and ruler
1) Take the garbage bag at your table and measure the length and
width
- What is the area of the bag?
2) Place it on the floor and all members in your group should try to
stand on it – both feet should be on the bag.
- How many people are in your group? What is the population
density on the bag?
3) Now take the garbage bag and fold in half – what is the area?
- Can all of your group stand on the bag?
- What is the new population density?
4) Repeat step 3 by folding the bag one more time.
- Why wasn’t everyone able to stand on the bag?
- What were you competing for?

5. More characteristics of populations
REVIEW:
• What do living things need to grow and reproduce?
– Can these populations grow forever?
– Why not? LIMITING FACTORS
• Another characteristic of
populations is called
carrying capacity
• Imagine a population of
rabbits increases each year.
Is there a limit to the supply
of resources in that
environment?
• YES: after some time the environment will not have enough
resources for the rabbits to survive or reproduce and the
population will stop increasing

6. Carrying Capacity
• (17– 9 pg. 490)
– This means the environment has reached the CARRYING
CAPACITY
– Carrying capacity is the largest number of individuals an
environment can support and keep healthy for a period of time
– What do you think happens when the population becomes higher
than the carrying capacity?

7. Human growth
• What are some limiting factors to human
population growth?
– Water
– Food
– Living space
– Pollution
– Disease
• To measure our human impact on nature, we
measure our ecological footprint (eco-footprint)

8. Eco-footprint
• How do we impact the earth and
create our footprint?
– Food
– Energy use
– Transportation
• If everyone on Earth lived the way the AVERAGE
person in North America did, we would need 3.8
Earths to support all of the people

9. Homework questions to answer about Ecological
Footprint:
• To calculate your eco-footprint:
http://ecoguru.panda.org/#/calculator/help
http://www.powerhousemuseum.com/education/ecologic/bigfoot/bigfoot20
07/
QUESTIONS:
1) What is the size of your Ecological Footprint? How many planets would
we need if everyone in the world had your Ecological Footprint?
2) How does your Footprint compare with those of people in other countries
in the world?
3) What parts of your lifestyle do you think contributed the most to the size of
your Footprint?
4) What changes to your lifestyle can you make to reduce your ecological
footprint? You should have one change for food, water use, energy use, and
transportation.
**PLEASE answer in full sentences and HAND THIS IN CLASS THURSDAY,
OCTOBER 28TH**