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Cogito

Grade 3 Math · Chapter 3 · Lesson 1

Practice Worksheet

Breaking an Array Apart

A hard fact is two easy facts in disguise.

10 problems · about 14 minutes · 3.OA.B.5

NameDate

Figure — use these to answer the problems

Cut the array after 5 columns. Read the two smaller products.

7 × 8 = 56

7 × 8 = (7 × 5) + (7 × 3) = 35 + 21 = 56

Rows7
Columns8
Cut after this column5
Figure 1

Warm-Up Review

From earlier lessons. Loosen up before the new work.

3 problems

  1. From “Litres and Millilitres”

    How many millilitres are in one litre?

    Answer

  2. From “Grams and Kilograms”

    How many grams are in one kilogram?

    Answer

  3. From “Time Intervals”

    From 7:45 to 8:10. How many minutes?

    Answer

Warm Up

Straightforward practice. Get the method working first.

3 problems

  1. 7 × 8 = ?

    Answer

  2. Why cut an array in two?

    • To make two facts you already know.
    • To make the answer smaller.

  3. 7 × 6 = ? Try (5 × 6) + (2 × 6).

    Answer

Build It Up

The same ideas with more to keep track of.

1 problem

  1. 9 × 4 = ? Try (5 × 4) + (4 × 4).

    Answer

Stretch Yourself

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

3 problems

  1. 8 × 7 = ? Try (5 × 7) + (3 × 7).

    Answer

  2. Splitting a Six

    6 × 7 split as (5 × 7) + (1 × 7). What is 35 + 7?

    Answer

  3. Splitting an Eight

    8 × 6 split as (4 × 6) + (4 × 6). What is 24 + 24?

    Answer