☰ Year plan · Mathematics

Length and solid shapes

Week 11 · Measuring length and solid shapes · 3 lessons
2

How long is a meter?

Discover Mathematics P2: Term 1, Lessons 41–50
GoalKnow that 1 meter is 100 centimeters and estimate lengths of about 1, 10, 50 and 100 cm.
New words
meter (m) · a long unit of length, 100 cmestimate · guess a length without measuringbenchmark · a length you know well, used to compare
Explanation

For long things we use a bigger unit, the meter. One meter is 100 centimeters. A meter stick is 100 cm long. To estimate without a ruler, use lengths you know. The width of your fingertip is about 1 cm. A new crayon is about 10 cm. Your arm from your shoulder to your fingertips is about 50 cm. A door handle is about 100 cm, which is 1 m, above the floor.

LengthAbout as long as
1 cmyour fingertip’s width
10 cma new crayon
50 cmyour arm, shoulder to fingertips
100 cm = 1 ma door handle’s height
Worked examples
50 cm50 cm100 cm = 1 m
A meter stick is 100 cm long. Cut it in two halves and each half is 50 cm.
1 m1 m2 m
A bed is about 2 meters long. That is 100 cm + 100 cm = 200 cm.
cmm
Use cm for small things like a pencil. Use m for long things like a bus.
Class activity

Find a meter. Cut a piece of string as long as 100 cm using a ruler, or use a meter stick. Walk around the home and find three things that are shorter than the string, and three that are longer. Which was easier to guess, short or long?

Practice
1
About how long is a new crayon: 1 cm, 10 cm or 100 cm?
2
About how wide is your fingertip?
3
How many centimeters make 1 meter?
5050?
4
Ziad’s rope is 2 m long. How many centimeters is that?
5
Choose cm or m: the length of a bus, and the length of a pencil.