Adding and Subtracting Within Twenty

Stage 2 of 23 Strand 1 of 2 3 lessons

3 illustrated lessons, each teaching the why before the how.

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Number Bonds to Ten #

The pairs that make ten, known by heart.

Knowing the pairs that make ten makes every later sum quicker

Look at the circles: 10 is 6 + 4.

7 + ? = 10. Take the part from the whole: 10 − 7 = 3.

Now you

4 + ? = 10

5 + ? = 10

What is left when part is removed.

Taking away finds the missing part when you know the whole and one part

4 and what make 9?

Take the whole − the part you know. 9 − 4 = 5.

Now you

8 − 4

9 − 6

Get to ten first, then cross it.

Getting to ten first makes crossing it easy

8 + 5. Start at 8: one jump of +5. Where does it land?

Split the 5 into 2 + 3. Jump +2 first to make 10.

Then +3 to make 13. So 8 + 5 = 13.

Now you

7 + 8

7 + 9