Choosing the Correct Units of Measure | 2nd Grade PDF Measurement ... - Free Printable

Let’s go through each question one by one and think about what makes sense for the size of each object.

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Question 1: Which one is 5 mm long?

- An ant → Ants are tiny. About 5 mm sounds right.
- Your arm → Way too big — that’s like 50 cm or more!
- A bus → Huge! That’s many meters long.

✔ So, An ant is 5 mm long.

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Question 2: Which one is 15 cm long?

- A football pitch → That’s huge — over 100 meters!
- A mobile phone → Most phones are around 14–16 cm long. Perfect!
- A dog → Even a small dog is bigger than 15 cm (that’s only about 6 inches).

✔ So, A mobile phone is 15 cm long.

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Question 3: Which one is 20 m long?

- A tennis court → Yes! A standard tennis court is about 23.77 m long — close enough to 20 m for this level.
- A toothbrush → Nope, that’s like 15–20 cm.
- A car → Most cars are 4–5 m long.

✔ So, A tennis court is 20 m long.

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Question 4: How would you measure...

We need to pick the best unit: mm (millimeters), cm (centimeters), or m (meters).

a) A giraffe?
Giraffes are very tall — several meters.
→ Use m

b) A pencil?
Pencils are about 15–20 cm long.
→ Use cm

c) A house?
Houses are big — measured in meters.
→ Use m

d) Your height?
Kids’ heights are usually between 100–180 cm, but we often say “1.5 m” etc. Either cm or m works, but since it says “your height,” and kids often use cm, let’s check:
Actually, both are used — but for precision, cm is common for people’s height in school settings. However, in many places, m is also fine. But looking at typical worksheets, they expect cm for human height unless specified otherwise. Wait — actually, let’s think:
If you’re 130 cm tall, that’s 1.3 m. Both correct, but since the options include both, and for accuracy with smaller numbers, cm is better for kids’ height.
BUT — wait, in real life, doctors might use cm, but in everyday talk, we say “I’m 1.3 meters.” Hmm. Let’s see the pattern:
For things under 1 meter, use cm. For things over 1 meter, use m. Since most kids are over 1 meter, maybe m? Actually, no — in measurement lessons, they teach that for human height, cm is precise and commonly used in schools. I’ll go with cm.

Wait — let me double-check common curriculum standards. In US elementary math, for grade 3–4, they often use cm for height when measuring with rulers, but m for larger objects. Actually, let’s look at the other items:

e) Cereal box → cm
f) Screw → mm
g) Newborn baby → cm (since babies are ~50 cm)

So for consistency, if newborn baby is cm, then your height should also be cm? But your height is bigger. Actually, newborns are measured in cm (like 50 cm), and older kids too (like 130 cm). So yes — cm for human height in this context.

But wait — some systems use m. Let me think again. The key is: which unit gives a reasonable number without decimals?

- If you’re 1.3 m → that’s fine.
- If you’re 130 cm → also fine.

But in the worksheet, for “a house”, they’ll want m. For “pencil”, cm. For “screw”, mm.

For “your height”, since it’s likely between 100–180 cm, using cm avoids decimals. So I’ll choose cm.

Actually, let me confirm with logic:
mm is for tiny things (screws, ants)
cm is for medium things (pencils, books, people’s height)
m is for large things (houses, courts, giraffes)

Yes — so:

d) Your height → cm

e) A cereal box?
About 25–30 cm tall → cm

f) A screw?
Very small — maybe 1–2 cm, but often measured in mm for precision → mm

g) A newborn baby?
Around 50 cm long → cm (not m, because 0.5 m is awkward; not mm, because 500 mm is too big a number)

Wait — newborns are about 50 cm, so cm is perfect.

Let me write them all down clearly:

a) Giraffe → m
b) Pencil → cm
c) House → m
d) Your height → cm
e) Cereal box → cm
f) Screw → mm
g) Newborn baby → cm

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Now, let’s compile the final answers.

Final Answer:
1) An ant
2) A mobile phone
3) A tennis court
4)
a) m
b) cm
c) m
d) cm
e) cm
f) mm
g) cm