The idea, step by step
What is missing?
A blank is a number we have not found yet. In 6 + __ = 10, we know the starting part and the whole.
Count on from six to ten. The number of steps is the missing part.
Put your answer back
Read the whole calculation with your answer in the blank. It must tell a true number story.
In 14 − __ = 9, ask how many you remove from fourteen to leave nine. Check by joining nine and the removed amount.
A common trap
Writing the whole in the blank without checking.
Instead: A blank is not always the answer to an addition. Read what is known and check the completed calculation.
See the thinking
A missing part
Find the blank: 6 + __ = 10.
- Start at six.
- Count seven, eight, nine, ten: four steps.
- Check: six and four make ten.
A missing removal
Fourteen marbles are in a bag. Some are taken out. Nine remain. How many were taken out?
- The whole was fourteen.
- Nine stay in the bag.
- Five were removed because nine and five make fourteen.
Check your understanding
Complete: __ + 5 = 12.
Show answer
7
Seven and five join to make twelve.
Your turn
6 questions · Work at your own pace.
Read the questions online
- Complete: 4 + __ = 9.
- Complete: __ + 3 = 11.
- Complete: 16 − __ = 10.
- Complete: __ − 5 = 8.
- A basket needs twelve apples. It has seven. How many more are needed?
- Sam puts 4 in the blank: 8 + __ = 13. Check and correct the answer.
Read the worked solutions
- Complete: 4 + __ = 9.
Count five more from four to reach nine.
5 - Complete: __ + 3 = 11.
Eight and three make eleven.
8 - Complete: 16 − __ = 10.
Removing six from sixteen leaves ten.
6 - Complete: __ − 5 = 8.
The starting whole was eight and five joined: thirteen.
13 - A basket needs twelve apples. It has seven. How many more are needed?
7 + 5 = 12.
5 apples. - Sam puts 4 in the blank: 8 + __ = 13. Check and correct the answer.
8 + 4 is 12. 8 + 5 is 13.
The blank should be 5.
Curriculum reference & lesson scope
Australian Curriculum v9 and SA Curriculum Mathematics
Year 1 additive situations and number bonds within twenty.
Official curriculum source ↗