1. Measurement
Chapter 37

2. Length-- Measured in cm, m, km.
Use a meter stick or a ruler to measure the length of a straight line.
An opisometer can be used to measure the length of a curved line
A Vernier callipers can be used to measure the internal and external diameters of cylinders.

3. opisometer

4. Trundle wheel

5. Area—measured in cm2, m2, The area of a rectangle = length by breadth.
Area of circle = π r2.
To find the area of an irregular shape—use graph paper.

6. Volume—measured in cm3, m3.
The volume of an object is the amount of space it takes up.
The volume of a rectangular block = (Length x Breadth x Height)

7. Volume of a Liquid
The volume of a liquid is found by pouring it into a measuring (graduated) cylinder.

8. Volume of a small object
The graduated cylinder can also be used to measure the volume of an object. If you place it in the cylinder and you measure how much the water goes up by. This is the same volume as the volume of the object.
What is the volume of the small Stone?
Answer:
10cm3 - 8cm3 = 2cm3

9. Volume of a large object
To find the volume of a large irregular shaped object—use an overflow can.
If the object is too big to fit into a graduated cylinder, place it in an overflow can which is filled to the brim with water. The object pushes out a volume of water equal to its own volume.

10. What is the volume of the large stone?
Answer:
The volume of the large stone is 14cm3.

11. Mass The mass of an object is the amount of matter in the object.
To measure the mass of an object we use a balance.
What is the mass of the stone?
Ans:
34.67 grams

12. Time—measured in s, min, hrs
Use a watch to tell the time.
Time is measured in seconds, minutes, and hours.
How many seconds are in a minute?
60 sec in a minute
How many minutes are in an hour?
60 minutes in an hour
How many hours are in a day?
24 hours in a day