Why Same-Size Units?

Bigger units give a smaller number.

10 problems · about 11 minutes · 1.MD.A.2

NameDate

Figure — use these to answer the problems

The same pencil, measured two ways.

Measured in small cubes

Measured in big blocks

Small cubes8

Big blocks4

Figure 1

From earlier lessons. Loosen up before the new work.

6 problems

From “Measuring With Cubes”
A stick takes 6 cubes laid end to end. How long is it?
Answercubes
From “Putting Three in Order”
Ropes are 3, 9 and 6 cubes. How long is the longest?
Answer
3
From “Using a Third Thing”
A rope is shorter than a string. The string is shorter than a pole. Is the rope shorter than the pole?
- Yes.
- No.
4
From “Longer Than, Shorter Than”
Why must you line up one end before comparing?
- Otherwise you cannot tell which is longer.
- To make it look neat.
5
From “True or False to Twenty”
Is 13 − 9 = 2 + 2 true?
- True. Both are 4.
- False.
From “Missing Numbers to Twenty”
8 + ? = 12
Answer

Straightforward practice. Get the method working first.

3 problems

7
Why must you say which unit you used?
- Because a number alone does not say how long.
- Because it is polite.
8
A rope is 6 big blocks. In small cubes, would the number be more than 6?
- Yes, more than 6.
- No, fewer than 6.
9
If you swap to smaller units, does the number go up or down?
- Up. You need more of them.
- Down.

Mixed problems. Work out what kind of question it is before you start.

1 problem

10
Two Rulers
A desk is 10 small cubes long. Measured in big blocks, will the number be bigger or smaller?
- Smaller, because each block covers more.
- Bigger.