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Cogito

Grade 3 Math · Chapter 4 · Lesson 4

Practice Worksheet

Breaking a Big Area Apart

The distributive property, in shapes.

10 problems · about 13 minutes · 3.MD.C.7

NameDate

Figure — use these to answer the problems

Cut the rectangle and read the two areas.

4 × 9 = 36

4 × 9 = (4 × 5) + (4 × 4) = 20 + 16 = 36

Height4
Width9
Cut after this column5
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

3 problems

  1. From “Finding a Missing Side”

    Area 42, one side 6. What is the other side?

    Answer

  2. From “Area by Multiplying”

    A rectangle 8 by 7. What is its area?

    Answer

  3. From “What Area Is”

    A rectangle 7 across and 3 down. What is its area?

    Answer

Warm Up

Straightforward practice. Get the method working first.

3 problems

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

    Answer

  2. Does splitting a rectangle change its area?

    • No. The pieces still cover the same space.
    • Yes. It gets smaller.

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

    Answer

Build It Up

The same ideas with more to keep track of.

1 problem

  1. Area of 6 by 8, split as 6 by 4 and 6 by 4?

    Answer

Stretch Yourself

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

3 problems

  1. Area of 7 by 9, split as 7 by 5 and 7 by 4?

    Answer

  2. The Long Room

    A room 3 by 12. Split it into 3 by 10 and 3 by 2. What is the total area?

    Answersquare units

  3. The Wall

    A wall 5 by 11. Split it into 5 by 10 and 5 by 1. What is the area?

    Answersquare units