Examples of what pupils should know and be able to do
Pupils need to know how to use the sign change key on a calculator.
Calculate
- 62 + -51 =
- -87 + 90 =
- -3 + = 7
- 5 - -3 =
- -4 - -5 =
- 2 - = 7
For a fact such as -3 × 2 = -6, write three other facts, i.e. 2 × -3 = -6, -6 ÷ 2 = -3, -6 ÷ 3 = -2
- Directed Numbers question - Rtf (rich text format) document (102Kb)
- Negatives question - Rtf (rich text format) document (38Kb)
Probing questions
‘Adding two numbers gives a bigger number.’ When is this statement true and when is it false?
‘Subtraction always gives a smaller number.’ When is this statement true and when is it false?
3 × −4 = −12. Give me some related facts.
−10 + 2 = 8. Give me some related facts.
The answer is −7. Can you make up some addition/subtraction and multiplication/division calculations with the same answer?
The answer on your calculator is −144.
What question might you have keyed in to get this answer?
What if pupils find this a barrier?
If necessary refer back to Step 5.
- Pupils need to be secure that 1 add −1 is zero and then use this
to calculate for example:
1 + 1 + -1 + 1 =
Then move on to
3 + -3 = - Extend patterns such as:
2 + 1 = 3
2 + 0 = 2
2 + -1 = 1
2 + -2 = 0
2 + -3 = -1 - Extend patterns such as:
2 × 2 = 4
1 × 2 = 2
0 × 2 = 0
-1 × 2 = -2
-2 × 2 = -4 - Pupils need to be able to use the sign change key on a calculator.
- Set pupils puzzles such as magic squares, number pyramids.
- Set pupils multiplication tables with integers from -5 to +5.
Some pupils may be able to do the calculations but need reminding what an integer is.
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