1. The Nature of Science and
Technology
Chapter 2 – Section 1

2. • Measurement – A Common Language
– A Standard Measurement System
• Metric System
• International System of Units (SI)
– Length
• Units of Length
• Measuring Length
– Mass
• Units of Mass
• Measuring Mass
• Difference Between Mass and Weight
– Volume
• Volume of Liquids, Solids, Irregular Solids
– Density
• Units of Density
• Densities of Common Substances
– Time
• Units of Time
• Measuring Time
– Temperature
• Units of Temperature
• Measuring Temperature

3. Key Concepts
• Why do scientists use a standard
measurement system?
• What are the SI Units of measure for
length, mass, volume, density, time, and
temperature?
• How are conversion factors useful?

4. Standard Measurement System
• Metric System
– Developed in France (1790s)
– Universal system called the Metric System
– System of Measurement based on the
number 10

5. Standard Measurement System
• International System of Units (SI)
– Version of metric system used by modern
scientists
– Scientists use SI units to measure length,
volume, mass, density, temperature, and time
– Standard system of measurement allows
scientists to compare data and
communicate with each other about their
results

6. SI Units
• Based on multiples of 10
• Each unit is 10 times larger than the next
smallest unit and one tenth (1/10) the size
of the next largest unit
• Refer to Figure 1 – Pg 45

7. Length
• Units of Length
– Distance from one point to another
– The basic unit of length in the SI system is
the meter (m).
– To measure smaller objects, use centimeter
(cm) or millimeter (mm)

8. Length
• Measuring Length
– Tools – Metric ruler
• Centimeter markings

9. Mass
• Mass is a measure of the amount of
matter an object contains.
• Units of Mass
– The basic unit of mass in the SI system is
the kilogram (kg).
– To measure the mass of smaller objects, use
gram (g) as the unit

10. Mass
• Measuring Mass
– Balance
• Triple Beam Balance
– Appendix C for directions

11. Mass
• Difference Between Mass and Weight
• Weight is a measure of the force of
gravity acting on an object

12. • Mass is a measure
of the amount of
matter an object
contains.
• Weight is a measure
of the force of
gravity acting on an
object

13. Learning Check
• What is the basic unit of length in the SI
system?
• What is mass?
• What is the basic unit of mass in the SI
system?

14. Volume
• Volume is the amount of space an
object takes up.
• Volume of Liquids
– To measure the volume of a liquid, use a unit
known as the liter (L)
– For smaller volumes use milliliters (mL)

15. Volume
• Volume of Rectangular Solids
– Volume of a solid object, use cubic centimeter
(cm3)
– For solids with larger volumes, scientists
use the SI unit known as the cubic meter
(m3)
– Volume = Length x Width x Height
– Example: 20cm x 6cm x 25cm = 3000 cm 3

16. Volume
• To calculate volume… (pg 50 and 51)
– Multiply the numbers
– Multiply the units
– ***Make sure you use the same units for all
measurements when calculating the volume
of a regular solid***

17. Volume
• Volume of Irregular Solids
• Can you measure length? Width? Or
Height???
• Instead… try immersing the object in
water
– Water level will rise
– Displacement of volume can be determined

18. Vocabulary: Meniscus
• The curved upper surface of a liquid in a
column of liquid
• Draw picture

19. Density
• The measure of how much mass is
contained in a given volume
• Density = Mass/Volume

20. Density
• Units of Density
– Density is made up of two other
measurements
• Mass
• Volume
– An object’s density is expressed as a
combination of two units.
– Example: grams per cubic centimeter
– Example: grams per milliliter (g/mL)

21. Densities of Common Substances
• Figure 6 – Pg 53

22. Time
• Units of Time
• The second (s) is the SI unit
used to measure time.

23. Time
• Measuring Time
– Clocks
– Watches
• Look at conversions for time (pg 53)

24. Temperature
• Units of Temperature (pg 54)
– Celsius temperature scale
– Water freezes at 0 degrees Celsius
– Water boils at 100 degrees Celsius
– Human body temperature is 37 degrees
Celcius
– Kelvin scale (K) is the official SI unit for
temperature

25. Temperature
• Measuring Temperature
– Thermometer

26. Converting Between Units
• Need to know conversion factor
• A conversion factor is an equation that
shows how two units of measurement are
related

27. Converting Between Units (pg 55)
• Write down the measurement you want to
convert
• Find conversion factor that relates the two units
you are converting
• Write conversion factor as a fraction (include
units)
• Multiply the measurement you are converting
from by the fraction
– Units will cancel out with the units in the denominator
of fraction

28. Chapter 2: Section 2
Mathematics and Science

29. Estimation
• An estimation is an approximation of a
number based on reasonable
assumptions
• Scientists rely on estimates when they
cannot obtain exact numbers
• Not the same as guessing because an
estimate is based on known information!

30. Accuracy
• Refers to how close a measurement is to
the true or accepted value

31. Precision
• Refers to how close a group of
measurements are to each other

32. Accuracy and Precision in
Measurements
• Both accuracy and precision are important
when you make measurements
• See Figure 11 – pg 62

33. Significant Figures
• The digits included in a measurement
• Include all of the digits that have been
measured exactly, plus one digit whose
value has been estimated

34. Significant Figures
• Adding and Subtracting
– The answer can only have as many figures
after the decimal point as the measurement
with the fewest figures after the decimal

35. Percent Error
• Percent error calculations are used to
determine how accurate, or close to the
true value, an experimental value really is

36. • Percent error = Difference between
experimental value and true value/True
value x 100%

37. • A low percent error means that the result
you obtained was very accurate
• A high percent error means that your
result was not very accurate

38. Mean, Median, and Mode
• Mean – Add up all numbers and divide by
the number of data added up
• Median – Middle number in a row of
numbers (lowest to highest)
• Mode – Numbers that appears the most in
a given set of data