Lesson overview:Comparing Strategies
- In today's lesson, we will learn to compare strategies around subtraction. We will discuss how efficient some strategies are, such as shifting to preserve the 'same difference' and make calculations easier.
- In today's lesson, we will learn to compare strategies around subtraction. We will discuss how efficient some strategies are, such as shifting to preserve the 'same difference' and make calculations easier.
Extending calculation strategies and additive reasoning:
- Adjusting addends
- Same sum' with larger numbers
- Same sum' with decimals
- Balancing equations using the 'same sum' strategy
- Balancing equations using compensation
- Balancing equations: Does the order of addends matter?
- Increasing an addend
- Decreasing an addend
- Solve calculations mentally by relating them to known facts
- Find an unknown addend
- Introduction to same difference
- Same difference in context
- Use the Language of Minuend, Subtrahend, and Difference
- Transform calculations using the same difference
- Practice: Transforming Calculations to Make Them Easier to Solve Mentally
- Transform a subtraction calculation to make the written algorithm easier to apply
- Practice: 'Same Difference' in Different Contexts
- Balancing equations to find unknown values
- Explore how the difference changes when only the Minuend is changed
- Apply the generalisation about how the minuend and difference change to solve problems
- Explore how the generalisation can be used as a mental calculation strategy using Known facts
- Thinking flexibly
- Comparing Strategies
- The more we subtract, the less we are left with. The less we subtract...
- Contexts where the Minuend is Kept the Same, and the Subtrahend Increases
- Contexts where the minuend is kept the same, and the Subtrahend decreases
- Further practice to reason about how the change in the subtrahend changes the difference
- Explore problems in which the new difference must be found
- Balance Equations Where the Compensation Property of Same Sum Cannot Efficiently be Applied
- Balance Equations Where the Compensation Property of Same Difference Cannot Efficiently be Applied