MR. AUBE AND FRIENDS · TEACHING NOTES

Subtract with a number line

Show subtraction by moving back along a number line, counting each jump once. Try a little together and stop whenever you need.

Get ready

Paper, a pencil and a counter. Draw equally spaced marks from 0 to 10.

Put a counter on 8. Say: “We have eight. We are taking away three.”
Move back one space to 7, then to 6, then to 5. Count the jumps: one, two, three.
Say: “Three jumps back from eight lands on five.” Write 8 − 3 = 5 and check by taking three away from eight objects.

Show eight objects and remove three. Ask children to explain what changed.
Model the same action on a number line. Pairs take turns choosing a start and moving back one, two or three spaces.
Compare a counter model and a number-line drawing. Finish with 10 − 2 on paper.

“Where do we start? How many jumps will we make? Where did we land?”

Use five objects and take one away. Match that action to one jump back from 5 to 4 on the line.

Draw a fresh number line on paper. Ask the child to show 10 − 2 and explain what the start, jumps and landing number mean.

For 9 − 6, compare six jumps back from nine with counting up from six to nine. Explain how both methods show a difference of three.

Gr 2 · N9 · This practises part of the outcome. It is not an assessment of the whole outcome.

Let your child show, draw or tell you how they worked it out. One answer is a starting point for a conversation.

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