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The Difference Bar

Students explore mental strategies to calculate the difference between two numbers. The basic strategy employed is that the difference can be found by addition.

Teacher notes

  • 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.

Learning objects

The difference bar picture.

The difference bar: generate easy subtractions
The sums generated enable students to find the difference between a single-digit number and a double-digit number.

The difference bar picture.

The difference bar: make your own easy subtractions
Students create their own sums to find the difference between a single-digit and a double-digit number.

The difference bar picture.

The difference bar: generate hard subtractions
The sums generated enable students to find the difference between two double-digit numbers.

The difference bar picture.

The difference bar: make your own hard subtractions
Students create their own sums to find the difference between two double-digit numbers.

The difference bar picture.

The difference bar: go figure
This tutorial is designed for use by the student or as a demonstration tool for the teacher. It covers the strategies for solving differences, including rounding to 10 or compensating to the next 10 to help find the difference. It is amenable to a screen reader.

The difference bar picture.

Difference bars
This is an aggregated learning object combining the five other learning objects.