New
New
Year 2

Calculate the difference in different contexts

I can calculate the difference in different contexts.

New
New
Year 2

Calculate the difference in different contexts

I can calculate the difference in different contexts.

Lesson details

Key learning points

  1. You calculate the difference by counting on from the known part to the whole.
  2. The difference is the answer to a subtraction calculation.
  3. The difference is one of the parts that make the whole.

Common misconception

Children think that 'counting on' is used solely as a strategy in addition.

Children should be made aware that the strategy for 'counting on' can be used in addition but is used as a strategy for subtraction in this lesson where we are finding the difference between two numbers close in value.

Keywords

  • Difference - The amount which a number is greater or smaller.

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

  • Count on - A mental strategy used to add numbers.

Children should be encouraged to only use 'counting on' as a strategy for finding the difference when it is an efficient choice (when the numbers being compared are close in value).
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.
Which equation has been written to find the difference between 9 and 6?
9 + 6 = ?
Correct answer: 9 - 6 = ?
6 - 9 =?
Q2.
9 and 6 have a difference of
Correct Answer: 3, three
Q3.
Here, we are finding the difference between…
An image in a quiz
2 and 5
Correct answer: 5 and 7
7 and 2
Q4.
How many have we ‘counted on’ on the number line?
An image in a quiz
Correct Answer: 3, three
Q5.
Which pairs of numbers have the same difference of 5?
10 and 4
Correct answer: 9 and 4
Correct answer: 8 and 3
7 and 3
Q6.
If I know the difference between 10 and 6 is 4, working backwards, I also know the difference between ___ and ___ is 4
Correct answer: 9 and 5
Correct answer: 8 and 4
7 and 4
Correct answer: 6 and 2
5 and 3

6 Questions

Q1.
When would we be best to use the ‘counting on’ strategy to find the difference?
Correct answer: When the numbers are close together.
When the numbers are far apart.
If we cannot work out the answer.
Q2.
If a book costs £4 and a toy car costs £12, how would we efficiently calculate the difference in price?
Correct answer: Subtract £4 from £12
Count on from £4 to £12
Add £4 and £12
Q3.
A teddy costs £9 and a toy car costs £12, how would we calculate the difference in price?
Subtract £9 from £12
Correct answer: Count on from £9 to £12
Add £9 and £12
Q4.
It takes Sofia 4 minutes to walk to school. It takes Jun 12 minutes to walk to school. How much longer does it take Jun to walk to school than Sofia? minutes.
Correct Answer: 8, eight
Q5.
Jacob wants to buy a new pencil case that costs £12 and he has saved £9 so far. How much more money does Jacob need to save? £
Correct Answer: 3, three
Q6.
When playing a game, the difference between Izzy’s score and Lucas’ score is 3, Izzy scored 9 so how many points could Lucas have scored?
Correct Answer: 12, 6, twelve, six

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