Students explore mental strategies to calculate the difference between two numbers. The basic strategy employed is that the difference can be found by addition.
- A partitioning model is used to help students see the value of strategies such as rounding to 10, or compensating to the next 10 to help find the difference.
- The animation at the commencement of the learning object demonstrates some of the strategies, which are also available as 'hints' while students work.
- The printouts show how the student solved each equation.
The difference bar: generate easy subtractions
The difference bar: make your own easy subtractions
The difference bar: generate hard subtractions
The difference bar: make your own hard subtractions
The difference bar: go figure