Use number facts to solve addition and subtraction problems. | Maths

Starter quiz

Which number would complete the equation that comes next in the pattern?

'24' ✓
Use the first part-part-whole model to complete the pattern.

43 then 53 ✓

33 then 43

43 then 63

48 then 58
Use a known fact to find the missing number. 34 + ______ = 39

'5' ✓
Match the correct single digit fact to the equation that it could help solve.

5 - 2 = 3

⇔

35 - 2 = 33 ✓

7 - 4 = 3

⇔

97 - 4 = 93 ✓

3 - 2 = 1

⇔

33 - 2 = 31 ✓
Sam writes an addition that she can solve using the known fact 5 + 4 = 9 The first addend and the sum both have 6 tens. What could her fact be?

65 + 5 = 70

64 + 4 = 68

63 + 4 = 67

65 + 4 = 69 ✓
What number did Sam subtract?

'6' ✓

Exit quiz

Alex bought a cake for 34 p and a bag for 3 p. How much did he spend altogether? Which part-part-whole model represents the problem?
Sam spent 37 p altogether on a box and a ribbon. The ribbon cost 3 p. How much did the box cost? Which known fact will help you solve the problem?

7 - 3 = 4 ✓

4 - 3 = 1

3 + 1 = 4
Choose the known fact that would help solve this problem. There were 54 cars in the car park. 3 were red. How many weren’t red?

4 - 1 = 3

1 + 3 = 4

4 - 3 = 1 ✓
Choose the known fact that would help solve this story. First, I had 75 books on the shelf. Then, 3 fell off. Now, how many books are on the shelf?

3 + 2 = 5

5 - 3 = 2 ✓

5 - 2 = 3
Sam’s sunflower was 86 cm tall and Alex’s sunflower was shorter. The difference between them was 4 cm. How tall was Sam’s sunflower. Write the known fact that would help you solve this problem.

'6 - 4 = 2' ✓
Choose the known fact that would help solve this problem. Sam saved £45 and then she saved £4 more. How much money did she save altogether?

5 - 4 = 1

5 + 4 = 9 ✓

9 - 5 = 4

Worksheet

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Lesson Details

Key learning points

Known facts can be used to help find new facts efficiently.
Known facts can be used to solve addition and subtraction problems.
Bar models can be drawn to help represent and understand problems.

Common misconception

Children may have difficulty knowing which operation is required to solve a problem, particularly in those involving finding the difference.

Encourage children to draw bar models or part-part-whole models to support their understanding of the structure of the problem and to articulate their thinking (as modelled in the lesson).

Keywords

Efficiently - Not wasting time or effort. An efficient strategy is one we can carry out easily.
Whole - All of something. Complete.
Part - A piece or section of a whole.