New
New
Year 1

Know that addition and subtraction are inverse operations

I can recognise addition and subtraction as the inverse of each other.

New
New
Year 1

Know that addition and subtraction are inverse operations

I can recognise addition and subtraction as the inverse of each other.

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Lesson details

Key learning points

  1. Addition is the inverse of subtraction. Addition can 'undo' subtraction.
  2. Subtraction is the inverse of addition. Subtraction can 'undo' addition.
  3. When a given amount is added to the start of a story, to 'undo' the change, we must subtract the same amount.
  4. When a given amount is subtracted from the start of a story, to 'undo' the change we must add the same amount.

Common misconception

Children may not understand the importance of the order of the numerals in equations, so may not understand that the amount added or subtracted is of key importance when undoing a change made.

Present errors to discuss and correct. Encourage children to use practical equipment to demonstrate how they know they are right or to show why an error made cannot be correct.

Keywords

  • Add - o find the total, or sum, by combining two or more parts (addends), or to increase an amount by adding another.

  • Subtract - To partition one part from another (the subtrahend from the difference), or to decrease an amount by taking an amount away.

  • Inverse - Inverse means the opposite in effect; the reverse of.

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).

Video

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6 Questions

Q1.
Does this story show addition or subtraction?
An image in a quiz
Correct answer: Addition
Subtraction
Q2.
What has been added in this story?
An image in a quiz
2 apples
Correct answer: 5 apples
7 apples
Q3.
What has been subtracted in this story?
An image in a quiz
6 counters
Correct answer: 5 counters
1 counter
Q4.
Which equation could represent this story?
An image in a quiz
6 + 3 = 9
3 - 6 = 9
Correct answer: 3 + 6 = 9
Q5.
Write an equation to represent this story. First, 10 friends were playing a matching game together. Then, 2 left to play another game. Now, 8 friends are playing the matching game together.
Correct Answer: 10 - 2 = 8
Q6.
What is missing from this story?
An image in a quiz
Correct answer: 9 counters
4 counters
5 counters

6 Questions

Q1.
What amount would we subtract to undo the addition? Use the cubes to help you.
An image in a quiz
Correct Answer: 3, three, Three
Q2.
What amount would we add to undo the subtraction?
An image in a quiz
Correct Answer: 6, +6, + 6
Q3.
How would we undo the change in this story? First, I had 9 pencils. Then, 2 pencils were taken. Now, I have 7 pencils. 9 − 2 = 7
Correct answer: 7 + 2 = 9
9 − 7 = 2
9 − 2 = 7
Q4.
Match each addition equation with the subtraction equation that can undo it.
Correct Answer:4 + 3 = 7,7 − 3 = 4

7 − 3 = 4

Correct Answer:5 + 1 = 6,6 − 1 = 5

6 − 1 = 5

Correct Answer:0 + 3 = 3,3 − 3 = 0

3 − 3 = 0

Q5.
Which of these pictures represent the inverse of 3 + 4 = 7
Correct Answer: An image in a quiz
An image in a quiz
An image in a quiz
An image in a quiz
Q6.
Which of these number pairs would complete this story?
An image in a quiz
Correct answer: 3 and 8
2 and 4
4 and 10