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Cogito

Grade 3 Math · Chapter 4 · Lesson 7

Practice Worksheet

Same Area, Different Shape

Rectangles can share an area and look nothing alike.

10 problems · about 13 minutes · 3.MD.C.7, 3.MD.D.8

NameDate

Figure — use these to answer the problems

Find every rectangle with an area of 12 and compare the perimeters.

Area · squares inside

12

Perimeter · walk around

14

3 × 4 = 12 · 3 + 4 + 3 + 4 = 14

Width3
Height4
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

3 problems

  1. From “Telling Area and Perimeter Apart”

    A rectangle 9 by 4. What is its area?

    Answer

  2. From “Perimeter”

    A rectangle 9 by 5. What is its perimeter?

    Answer

  3. From “Breaking a Big Area Apart”

    Area of 5 by 9, split as 5 by 5 and 5 by 4?

    Answer

Warm Up

Straightforward practice. Get the method working first.

3 problems

  1. A 2 by 9 rectangle. What is its area?

    Answer

  2. Which rectangle with area 36 has the smallest perimeter?

    • 6 by 6.
    • 4 by 9.

  3. A 2 by 6 rectangle. What is its perimeter?

    Answer

Build It Up

The same ideas with more to keep track of.

1 problem

  1. A 3 by 4 rectangle. What is its perimeter?

    Answer

Stretch Yourself

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

3 problems

  1. Both have area 12. Do they have the same perimeter?

    • No.
    • Yes.

  2. The Pen

    A pen with area 16 can be 4 by 4 or 2 by 8. Which needs less fence?

    • The 4 by 4.
    • The 2 by 8.

  3. The Long One

    A rectangle 1 by 12. What is its perimeter?

    Answerunits