Compare Lengths and Find the Difference

Students measure two objects and subtract to find how much longer one object is than the other, expressing the difference using a standard unit. Students practice interpreting comparison questions and writing difference statements.

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Grade 2 · Measuring Length · question 1 of 3

0 of 12

12 rungs. A star at the top.

Difference in inches?

Your answer:

How it is taught

0:00 of 3:16

To compare lengths, subtract the shorter from the longer.

The difference needs the same unit.

Read it: How much longer: subtract

A is 9 cm and B is 5 cm on the same ruler. A is 4 cm longer: 9 − 5 = 4.

Read A from 0: 9 cm.
Read B from 0: 5 cm.
Take the shorter from the longer: 9 − 5 = 4.

Both bars start at 0, so each end mark is that bar's length.

The part of A that sticks out past B is the difference.

Taking 5 from 9 leaves the 4 cm that sticks out past B.

Read both lengths from 0. Subtract to find how much longer.

Answering 9, the length of A, instead of how much longer A is.

How much longer means the difference: 9 − 5 = 4 cm.

A pencil is 11 cm long. A crayon is 5 cm long. How many cm longer is the pencil? — 6. Take the shorter from the longer: 11 − 5 = 6. The pencil is 6 cm longer.

12 cm − 8 cm

Today we'll compare two lengths and find the difference. Mia has two pencils on her desk.

She lines the first pencil up with her ruler. It's twelve centimeters long.

Grade 2 · How much longer is the first pencil than the second?

Then she measures the second pencil. It's eight centimeters long.

How much longer is the first pencil than the second one?

Look — this extra part of the first pencil sticks out past the second. That's the difference we want to find.

To find the difference, we subtract the smaller length from the bigger one: twelve minus eight.

Twelve minus eight is four.

So the first pencil is four centimeters longer than the second pencil.

When we compare lengths, we always subtract to find the difference. Nice work!

Now you try. Read how long this object is on the ruler. How long is it?

What you see

While they climb, your page writes one true line to ask about tonight, and a short note each Sunday.

MayaGrade 3 · Mathematics

Did you know?

A chessboard has 64 squares — share them out between the 8 rows and each row holds exactly 8.

Today’s goal: 1 star — one skill mastered, every rung of its ladder climbed
Climbing now: Divide within 100

An example student.

MayaGrade 3 · Mathematics

Maya earned 2 stars this week — Interpret multiplication as equal groups, which took 6 answers over 3 days before its star landed 3 days ago and Multiply by 6, 7, 8 and 9. Next up: Divide within 100.

An example week.

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