New
New
Year 7

Addition of positive and negative integers

I can use the mathematical structures that underpin addition to add positive and negative integers.

New
New
Year 7

Addition of positive and negative integers

I can use the mathematical structures that underpin addition to add positive and negative integers.

Lesson details

Key learning points

  1. It can help to think of a context when doing a calculation.
  2. Addition of negative integers can be made easier by considering zero pairs.
  3. Addition of large negative integers can be made easier using partioning to make zero pairs.

Common misconception

That addition will always make the result bigger.

If pupils are struggling with the concept that adding can make an integer smaller encourage them to use counters and form zero pairs.

Keywords

  • Additive inverse - The additive inverse of a number is a number that, when added to the original number, gives the sum of 0.

  • Zero pair - A number and its additive inverse make a zero pair.

  • Absolute value - The absolute value of a number is its distance from zero. E.g. 5 and (−5) are both 5 away from zero and so both have an absolute value of 5

Get pupils into pairs or groups. Each has a bag containing positive and negative counters. They take it in turns to take out some counters without looking and have to give the integer represented by those counters, whilst the others check.
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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6 Questions

Q1.
Select all the integers.
Correct answer: -44
-4.4
Correct answer: 0
Correct answer: 4
44.4
Q2.
Select all of the correct statements.
-2 < -3
Correct answer: -3 < -2
Correct answer: -2 > -3
Correct answer: -5 > -6
-6 > -5
Q3.
Starting with the lowest temperature, put these temperatures in order from coldest to warmest.
1 - $${-8}^\circ \text{C}$$
2 - $${-6}^\circ \text{C}$$
3 - $${-2}^\circ \text{C}$$
4 - $${0}^\circ \text{C}$$
5 - $${2}^\circ \text{C}$$
6 - $${6}^\circ \text{C}$$
Q4.
The temperature in Reykjavik is $${-5}^\circ \text{C}$$. It is $${3}^\circ \text{C}$$ warmer in Paris. What is the temperature in Paris?
$${-8}^\circ \text{C}$$
$${-3}^\circ \text{C}$$
Correct answer: $${-2}^\circ \text{C}$$
$${2}^\circ \text{C}$$
$${3}^\circ \text{C}$$
Q5.
Andeep has a balance of £1.50 at the school canteen. He buys a sandwich for £2.10, an apple for 25 p and some fruit juice for £1.15. What is Andeep's new balance?
£2
£1
£0
-£1
Correct answer: -£2
Q6.
A submarine is 200 metres below sea level. The submarine rises 150 metres and then dives down 300 metres. The submarine is now metres below sea level.
Correct Answer: 350, 350m, 350 m, 350 metres

6 Questions

Q1.
Match together each number with its additive inverse.
Correct Answer:-3,3

3

Correct Answer:4,-4

-4

Correct Answer:-1,1

1

Correct Answer:2,-2

-2

Q2.
Which integer does this set of counters represent?
An image in a quiz
(-11)
Correct answer: (-3)
(-2)
3
11
Q3.
Work out: 5 + (-4) =
Correct Answer: 1, one
Q4.
Work out (-3) + (-2)
5
1
(-1)
Correct answer: (-5)
Q5.
Starting with the calculation with the lowest answer, sort these calculations in order of size from lowest answer to highest answer.
1 - (-2) + (-4)
2 - (-3) + (-1)
3 - 2 + (-2)
4 - 3 + (-2)
5 - (-1) + 5
Q6.
Work out: 7 + (-14) + 12 + (-8) =
Correct Answer: (-3), -3, - 3, (- 3)