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Lesson · Grade 3 · Mathematics

Arrays: 3 rows of 4 and 4 rows of 3

  • Grade 3
  • Mathematics
  • 1 min 3 s
  • British Columbia
  • BC3-MA-14

Twelve dots in 3 rows of 4 are added row by row (4 + 4 + 4 = 12) and written as 3 × 4 = 12. A copy of the array is given a quarter turn so its 4 columns become 4 rows of 3 (3 + 3 + 3 + 3 = 12, so 4 × 3 = 12), and the video ends on the recap that 3 rows of 4 and 4 rows of 3 both make 12.

Concept: Arrays: multiplying with rows and columns

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In one sentence

The question this lesson answers

How many dots are in this array?

Rows go across, and this array has 3 rows.

Transcript

What the lesson says

How many dots are in this array?

Rows go across, and this array has 3 rows.

The rows are all the same, with 4 dots in each row.

Add the rows: 4 plus 4 plus 4 is 12.

3 rows of 4 means 3 times 4, and that is 12.

Columns go up and down, and this array has 4 columns.

Now copy the array and give the copy a quarter turn.

The 4 columns are now 4 rows, with 3 dots in each row.

Add the rows: 3 plus 3 plus 3 plus 3 is 12.

4 rows of 3 means 4 times 3, and that is 12.

Both arrays have the same 12 dots, just turned.

3 rows of 4 and 4 rows of 3 both make 12.

Curriculum

Where this fits

British Columbia, Grade 3

Mathematics, Number: multiplication and division conceptsBC3-MA-14

Previous: Multiplying means equal groupsNext: Two Ways to Divide: Sharing and Grouping

The outcomes and strands follow the British Columbia curriculum.

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