The idea, step by step
Rows go across
An array is an arrangement with straight rows and columns. Every row has the same number of objects. This array has 3 rows of 4. Trace across each row before counting its dots.
Columns go down
The same array also has 4 columns of 3. Turning or describing the array another way does not add or remove objects. You can count by rows or by columns to check the same total.
A common trap
Mixing up the number of rows with the total.
Instead: A row is a group. Count how many objects are in each row as well as how many rows there are.
See the thinking
Count by rows
How many dots are in the 3-row array?
- There are 4 dots in each row.
- Count 4 + 4 + 4 = 12.
Make a different array
Arrange 10 counters in 2 equal rows. How many counters are in each row?
- Share the 10 counters between 2 rows.
- Each row has 5; check 5 + 5 = 10.
Check your understanding
An array has 2 rows of 6. How many objects are there?
Show answer
12
6 + 6 = 12.
Your turn
6 questions · Work at your own pace.
Read the questions online
- Count the dots in this array.
- How many rows and columns are in this array?
- Draw an array with 2 rows of 3 dots. How many dots?
- There are 4 rows of 5 chairs. How many chairs?
- Arrange 12 counters in 2 equal rows. How many in each?
- An array has 2 rows of 5. If you turn the page, it has 5 rows of 2. Has the total changed? Explain.
Read the worked solutions
- Count the dots in this array.
There are 2 rows of 4: 4 + 4 = 8.
8 dots. - How many rows and columns are in this array?
Trace three horizontal rows and two vertical columns.
3 rows and 2 columns. - Draw an array with 2 rows of 3 dots. How many dots?
3 + 3 = 6.
6 dots. - There are 4 rows of 5 chairs. How many chairs?
5 + 5 + 5 + 5 = 20.
20 chairs. - Arrange 12 counters in 2 equal rows. How many in each?
6 + 6 = 12.
6 counters. - An array has 2 rows of 5. If you turn the page, it has 5 rows of 2. Has the total changed? Explain.
Turning the arrangement does not change the objects.
No. There are still 10 objects.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Equal groups; arrays; repeated addition; sharing/grouping; twos facts; doubling and halving.
Official curriculum source ↗