Grade 2 · Maths · Lessons
Big units, small units
📏centimeter🪧meter📐inch🦶foot
Big and small units.The big ideaA smaller unit fits more times.
How it works
A smaller unit fits more times into the same length. A meter is 100 centimeters.
Using a big unit gives a small number. A small unit gives a big number.
Pick a sensible unit: centimeters for a crayon, meters for a room.
Example 1: Meters to centimeters
- A ribbon is 2 meters long. 1 meter is 100 centimeters.
- 100 + 100 = 200.
- The ribbon is 200 cm long.
Example 2: Choose a unit
- A crayon is about 10 centimeters long. An inch is longer than a centimeter.
- Fewer of the longer unit fit along the crayon.
- The crayon is about 10 cm, or about 4 in.
Example 3: A smaller unit gives a bigger number
- A room is 3 meters wide.
- In centimeters: 100 + 100 + 100 = 300.
- The same room is 300 cm wide: the smaller unit gives the bigger number.
Words to know
- unit
- A fixed amount used to measure.
- estimate
- A good guess.
Watch out
- A smaller unit means a bigger number.
- Say the unit with every measure.
- Check your guess is sensible.
Try it
- 1 meter is how many centimeters?
- A table is 2 meters long. How many centimeters?
- Which unit gives a bigger number for the same length: centimeters or meters?
- Would you measure a crayon in centimeters or meters?
Answers: 1. 100 · 2. 200 · 3. centimeters · 4. centimeters
For grown-upsAsk for an estimate before measuring at home, then check with a ruler.