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Lesson 1

Adjusting addends

Lesson 2

Same sum' with larger numbers

Lesson 3

Same sum' with decimals

Lesson 4

Balancing equations using the 'same sum' strategy

Lesson 5

Balancing equations using compensation

Lesson 6

Balancing equations: Does the order of addends matter?

Lesson 7

Increasing an addend

Lesson 8

Decreasing an addend

Lesson 9

Solve calculations mentally by relating them to known facts

Lesson 10

Find an unknown addend

Lesson 11

Introduction to same difference

Lesson 12

Same difference in context

Lesson 13

Use the Language of Minuend, Subtrahend, and Difference

Lesson 14

Transform calculations using the same difference

Lesson 15

Practice: Transforming Calculations to Make Them Easier to Solve Mentally

Lesson 16

Transform a subtraction calculation to make the written algorithm easier to apply

Lesson 17

Practice: 'Same Difference' in Different Contexts

Lesson 18

Balancing equations to find unknown values

Lesson 19

Explore how the difference changes when only the Minuend is changed

Lesson 20

Apply the generalisation about how the minuend and difference change to solve problems

Lesson 21

Explore how the generalisation can be used as a mental calculation strategy using Known facts

Lesson 22

Thinking flexibly

Lesson 23

Comparing Strategies

Lesson 24

The more we subtract, the less we are left with. The less we subtract...

Lesson 25

Contexts where the Minuend is Kept the Same, and the Subtrahend Increases

Lesson 26

Contexts where the minuend is kept the same, and the Subtrahend decreases

Lesson 27

Further practice to reason about how the change in the subtrahend changes the difference

Lesson 28

Explore problems in which the new difference must be found

Lesson 29

Balance Equations Where the Compensation Property of Same Sum Cannot Efficiently be Applied

Lesson 30

Balance Equations Where the Compensation Property of Same Difference Cannot Efficiently be Applied