1. Adding and Subtracting Directed Numbers
Projector Resources

2. Why is this ‘4’? 4

3. How much is this?

4. How much is this? 3

5. Making 3
Show me three more ways of making 3. Can you do one using 11 charges altogether?

6. How much is this?

7. How much is this? –2

8. How much is this?

9. How much is this?

10. How much is this?

11. How much is this? +3

12. How would you describe what happens here?

13. How would you describe what happens here?

14. How would you describe what happens here?
(+4) +

15. How would you describe what happens here?
(+4) + (–2) =

16. How would you describe what happens here?
(+4) + (–2) = (+2)

17. How would you describe what happens here?+2

18. How would you describe what happens here?
What do we get when we take away a negative?

19. How would you describe what happens here?
(+2) –

20. How would you describe what happens here?
(+2) – (–1) =

21. How would you describe what happens here?
(+2) – (–1) = (+3)

22. What’s the story here?

23. What’s the answer?
1 – (–2) =

24. What’s the answer?
1 – (–2) = 3

25. Working Together 1
Choose one of the three cards and match it with one of the calculations.
Write the answer to the calculation after the equals sign.
Check that the answer matches what you see in the drawing.
Do the same with the other two cards.
Make up drawings to fit the remaining three calculations and write down the answers to those three calculations.
The answers should match the drawings.
Everyone in the group should agree.

26. Calculations (1)

27. How can I draw (+2) – (+5)?

28. How can I draw (+2) – (+5)?
Another way of thinking of (+2)…

29. How can I draw (+2) – (+5)?
And another…

30. How can I draw (+2) – (+5)?
And another…
Do you agree that this is still (+2)?

31. How can I draw (+2) – (+5)?
And another…
How can I take away (+5)?

32. How can I draw (+2) – (+5)?
And another…
(+2) – (+5) =

33. How can I draw (+2) – (+5)?
And another…
(+2) – (+5) = (–3)

34. Working Together 2
Choose one of the three cards and match it with one of the calculations.
Write the answer to the calculation after the equals sign.
Check that the answer matches what you see in the drawing.
Do the same with the other two cards.
Make up drawings to fit the remaining three calculations and write down the answers to those three calculations.
The answers should match the drawings.
Everyone in the group should agree.

35. Calculations (2)