MA 4.05Subtraction Strip Board and Charts
The child uses the Subtraction Strip Board to find and record subtraction facts up to 18 − 9, then practices recall with the subtraction charts.
Presentation
- 1
Problem 14 − 5: 'We start with fourteen.' Cover the numbers 15–18 with a plain wood strip.
- 2
Place blue strip 5 so it ends at the right edge of 14.
- 3
Read the last uncovered number to the left of the blue strip: 9. Write 14 − 5 = 9.
- 4
Do two more together.
- 5
The child works through subtraction tables, such as all facts starting from 10, and records them.
- 6
Check each answer with the subtraction control chart, or with Addition Chart 1 (9 + 5 = 14).
- 7
Introduce the working charts in the same order as the addition charts, ending with recall from memory.
Extensions, easiest to hardest
- Write the related addition fact for each subtraction fact.
- Fact families: 5 + 9, 9 + 5, 14 − 5, 14 − 9.
- Recall subtraction slips without the board and check with the chart.
Control of error
The subtraction control chart; any answer can also be checked by adding it to the number taken away.
Ready to move on when the child…
- Records subtraction facts correctly using the board
- Recalls subtraction facts within 10 without the board
- Writes the related addition fact for a subtraction fact