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Lesson · Grade 4 · Mathematics

3 × 7 = 7 × 3: Equal Groups, Skip Counting and Arrays

  • Grade 4
  • Mathematics
  • 1 min 4 s
  • British Columbia
  • BC4-MA-16

Three plates of 7 dots show 3 equal groups of 7, written 3 × 7, and skip counting by 7s (7, 14, 21) gives 21. The groups then line up as the rows of an array, which turns a quarter turn into 7 rows of 3, and skip counting by 3s gives 21 again, so 3 × 7 is the same as 7 × 3.

Concept: Multiplication as equal groups, skip counting and arrays

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In one sentence

The question this lesson answers

How many dots are there in all?

There are 3 equal groups, with 7 dots in each group.

Transcript

What the lesson says

How many dots are there in all?

There are 3 equal groups, with 7 dots in each group.

We can write 3 groups of 7 as 3 times 7.

Skip count by 7s: 7, 14, 21.

So 3 times 7 is 21.

Now put each group in a row to make an array.

This array has 3 rows of 7, so it shows 3 times 7.

Now give the array a quarter turn.

Now there are 7 rows, with 3 dots in each row.

Skip count by 3s: 3, 6, 9, 12, 15, 18, 21.

So 7 times 3 is 21 too.

It is the same 21 dots, just turned.

So 3 times 7 is the same as 7 times 3.

Curriculum

Where this fits

British Columbia, Grade 4

Mathematics, Number: multiplication and division facts to 100 (introductory computational strategies)BC4-MA-16

Previous: 15.2 − 7.85Next: Division facts from multiplication facts

The outcomes and strands follow the British Columbia curriculum.

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