1. Aim: Understand how scientists work and the importance of measurement.
You will learn
The method scientists use to investigate a problem.
Learn how we observe things in the world and realise how our sense can give the wrong information sometimes.
Be able to understand the different units of measurement.
Learn how to measure length, the instruments used, and how to avoid errors.
Learn how to measure time, mass and temperature and their units.
Learn how to use common prefixes with regard to units of measure.

2. Keywords

3. Measurement and Units Scientific Method
The scientific method is a way to ask and answer scientific questions by making observations and doing experiments.
The steps of the scientific method are to:

4. Scientific Method Ask a Question Do Background Research
Suggest a Hypothesis (explanation)
Test Your Hypothesis by Doing an Exer ment
Analyze Your Data and Draw a Conclusion
Tell others your Results

5. Scientific Method
It is important for your experiment to be a fair test. A "fair test" occurs when you change only one factor (variable) and keep all other conditions the same.

6. Scientific Method

7. Measuring
Scientists do experiments and with measuring instruments can make accurate observations.
We cannot always trust our senses, one the reasons why measuring is important.

8. Measurment Which line is the longest a or b?
In fact they are both the same length.

9. Measurement Which man is the tallest?
In fact they are all the same height
So we must be careful of ours senses

10. Measuring Length
Length is measured in units called metres (m). Where did metres come from?
Show video clip on measurement.
Common
Units
1 m
100 cm 1m
1000 mm
1 km
1000 m

11. Measuring length

12. Measuring Length Metre stick (nearest mm) Measuring tape (nearest mm)
Callipers (nearest mm)

13. Measuring Length
Vernier Callipers (nearest 0.1 mm) measures small lengths and thicknesses.

14. Measuring Length
Opisometer (nearest mm) measures length of curved lines

15. Measuring Length
Trundle Wheel (nearest cm) measure longer lengths eg. Curved or straight lines on football pitches.

16. Measuring Mass
Mass is the amount of matter or stuff in an object, measured using electronic balance in grams (g) or kilograms (kg)
How can the mass of a liquid be measured?

17. Measuring Time
Time is measured in seconds, minutes, hours, days and years. Measured using a stopwatch in the laboratory.

18. Measuring Temperature
The temperature of an object is measure of how hot or cold an object is measured in degrees celcius (oC)
Temperature of the body is 37 oC
Pure water freezes at 0 oC and boils at 100 oC
Temperatures below 0 oC have a minus value.

19. Measuring Temperature
Four types of thermometer
(a) mercury (b) alcohol (c) digital (d) clinical

20. Units and Prefixes Prefixc Symbol Unit multiplied by milli- m
1/1000 or or 10-3
centi- c
1/100 or 0.01 or 10-2
deci- d
1/10 or 0.1 or 10-1
hecto- h
100 or 102
kilo- k
1000 or 103
mega- M
or 106

21. Area The area of a shape is the amount of surface enclosed by it.
Area is measured in cm2 or m2
1m2 = 1m x 1m
= 100cm x 100cm
= 10,000 cm2
Area of a rectangle = length by width.

22. Area
Area of a square = length by length

23. Area
The area of a triangle = half the base x perpendicular height.

24. Area
Area of circle = π x radius x radius (πr2)

25. Area EXAMPLE 1 Which of the following has the greatest area?
(1) a rectangle of length 12.5 m and width 4.
(2) a square of length 7 m
(3) a triangle of base 13 m and height 8 m.
Do the above problems in your copy book.
(1) area of rectangle = length x width
= 12.5 x 4
= 50 m2
(2) area of square = length x length
= 7 x 7
= 49 m2

26. Area (3) Area of a triangle = ½base x perpendicular height.
= 52 m2
EXAMPLE 2
How many times bigger is pizza A than pizza B if A has a radius of 20 cm and B a radius of 10 cm.
Area of Pizza A radius 20 cm
= πr2 = π 20 x 20 = 400π cm2
Area of Pizza B radius 10 cm
= πr2 = π 10 x 10 = 100π cm2
SO PIZZA A IS FOUR TIMES THE AREA OF PIZZA B

27. Volume The volume of an object is the amount of space it takes up.
Volume is measured in cubic metres (m3)
or cubic centimetres (cm3)
or litres = 1000 cm3
Volume in the laboratory is measured with
measuring pipettes Burettes
cylinders

28. Volume The volume of a regular object = length x width x height.
EXAMPLE
What is volume of a rectangular object length 10 m width 5 m and height 2 m
Volume = length x width x height
= 10 x 5 x 2
= 100 m3
How could you measure the
volume of stone?

29. Volume
Measuring the volume of an irregular object is got my displacement of a liquid (e.g. water)
either by the rise in water level or
displacement of water into
a measuring cylinder.