Centimetres and metres
We measure small things in centimetres, cm. We use a ruler. A short pencil is about 15 cm long. We measure long and tall things in metres, m. A door is about 2 m tall. A city bus is about 12 m long. 100 centimetres make 1 metre. So 2 m is 200 cm. Start at 0 on the ruler. Read the number at the end of the object.
Rana, how long is your rubber?
Let me see. I put it at zero. It is 5 centimetres long.
And how tall is our classroom door?
It is too tall for a ruler. We measure it in metres.
I think it is 2 metres tall.
Mostafa wants to measure his room. His desk is 1 metre long. His bed is 2 metres long. His pencil case is 20 centimetres long. His rubber is only 5 centimetres long. He uses centimetres for small things and metres for big things.
Measuring hunt. With a ruler, the child measures five small things (a pencil, a book, a rubber, a spoon, a hand) in centimetres and writes the numbers. Then the child walks one big step and the grown-up checks it with a metre stick or a long string: about how many steps make one metre?