Cogito
Grade 2 Math · Chapter 2 · Lesson 2
Centimetres and Metres
Big things need a bigger unit.
10 problems · about 11 minutes · 2.MD.A.1, 2.MD.A.3
What this lesson teaches
The child chooses between centimetres and metres for a given object and knows that 100 cm make 1 m.
- Centimetres suit things you can hold.
- Metres suit rooms and playgrounds.
- One metre is 100 centimetres.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Measuring in Centimetres: Where should one end of the object go?
Answer On the 0.
Why Starting at 0 makes the far end read the length directly.
Review — Two-Step Word Problems: 9 sweets. 5 more given. 6 eaten. How many are left?
Answer 8
Why 9 + 5 = 14, and 14 − 6 = 8.
Review — Choosing a Strategy: 9 + 7 = ?
Answer 16
Why 9 + 1 + 6 = 16.
Warm Up
Straightforward practice. Get the method working first.
3 problemsHow many centimetres are in a metre?
Answer 100
Why 1 metre = 100 centimetres.
Which unit would you use for a bedroom wall?
Answer Metres.
Why Metres suit anything room-sized or bigger.
How many centimetres make one metre?
Answer 100
Why It is a round hundred.
Build It Up
The same ideas with more to keep track of.
1 problemWhich unit fits a football pitch?
Answer Metres.
Why It is much bigger than a room.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsWhich unit fits a paperclip?
Answer Centimetres.
Why It fits on your fingertip.
Around the School: Which unit would you use to measure the length of a pencil case?
Answer Centimetres.
Why A pencil case is small, so centimetres fit.
The Corridor: Which unit would you use to measure a corridor?
Answer Metres.
Why Long things are measured in metres.