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 cm3

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 Look at conversions for time (pg 53) 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. Mathematics and Science
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