Describing arrays

Learning focus

Learn how to use an array to see the commutativity of multiplication facts (for example 3 x 5 is the same as 5 x 3).

This lesson includes:

• two videos
• three activities

Learn

Repeated addition and multiplication: Describing arrays

Watch this animation from 1st Level Maths and Numeracy. Fin and Snoot count Meebs by putting them into equal rows and columns.

What is an array?

An array is a way of representing multiplication facts in a diagram or picture. It is always rectangular and made up of rows and columns.

An array is helpful for calculating multiplication statements, for example, 2 x 4 which can be shown using this array:

• There are 2 rows of apples and 4 apples in each row.

• There are 4 columns of apples and 2 apples in each column.

This array shows the multiplication statements 2 x 4 and 4 x 2.

The array has 8 apples in total. This tells us that 2 x 4 and 4 x 2 are both equal to 8.

2 x 4 = 8 and 4 x 2 = 8

Example 1:

Here is an array to show a multiplication fact:

• There are 3 rows of sweets and 5 sweets in each row.

• There are 5 columns of sweets and 3 sweets in each column.

This array shows the multiplication statements 3 x 5 and 5 x 3.

The array has 15 apples in total. This tells us that 3 x 5 and 5 x 3 are both equal to 15.

3 x 5 = 15 and 5 x 3 = 15

Top tip

Remember multiplication is commutative.

4 x 3 is the same amount as 3 x 4.

4 lots of 3 is the same amount as 3 lots of 4.

Example 2:

Here is an array to show 6 x 2

• Can you see 6 lots of 2?

• Can you see 2 lots of 6?

• How many footballs are there in the array?

This array shows that 6 x 2 = 2 x 6.

Now let's recap with this video from KS1 Maths. Can you think how you might show 3 x 7 using an array?

Practise

Activity 1

1. Can you draw an array to show 3 x 4?

2. Which other multiplication fact does it show?

Remember

An array is a rectangular diagram to show a multiplication fact. It always has rows and columns and shows that multiplication is commutative.

Activity 2

Make an array activity

Try this interactive activity to see if you can answer the question by making your own array.

Activity 3

Worksheet: Using arrays

This worksheet from Classroom Secrets Kids contains three tasks about using arrays. Have a go and see if you can get them all correct.

Finished? Check here for the answer sheet

Play

Test your skills on this topic even further by playing Karate Cats Maths - see if you can collect a new costume for your cat!

There's more to learn

Have a look at these other resources.