# Deriving addition and subtraction facts by using given calculations

## Lesson details

### Key learning points

1. In this lesson, we will derive addition and subtraction facts by using given calculations, consider how the whole or parts have changed and the impact this has on the new calculation.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

Share with pupils

## Worksheet

Share with pupils

## Starter quiz

Share with pupils

### 5 Questions

Q1.
If I know 3 + 3 = 6, then I know...
30 + 10 = 40
Correct answer: 30 + 30 = 60
40 + 60 = 100
Q2.
If I know 3 + 5 = 8, then I know...
300 + 400 = 700
Correct answer: 300 + 500 = 800
600 + 200 = 800
Q3.
What's the missing part in the following equation: 220 + ___ = 550
110
440
Q4.
What's the missing part in the following equation: 110 + ___ = 660
440
530
Q5.
Here are three derived facts, based on the fact 3 + 5 = 8. Which is incorrect?
Correct answer: 13 + 15 = 18
30 + 50 = 80
3000 + 5000 = 8000

## Exit quiz

Share with pupils

### 5 Questions

Q1.
What's the same? What's different? 364 + 302 = 666 and 374 + 302 = 676
1 part has decreased by 10
Correct answer: 1 part has increased by 10
1 part has increased by 100
Q2.
What's the same? What's different? 764 - 204 = 560 and 754 - 204 = 550
Correct answer: 1 part has decreased by 10
1 part has decreased by 100
1 part has increased by 10
Q3.
What's the same? What's different? 3672 + 1474 = 5146 and 3972 + 1474 = 5446
1 part has decreased by 300
1 part has increased by 30
Correct answer: 1 part has increased by 300
Q4.
If... 362 + 205 = 567 then... 262 + 205 = ?