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Year 2 - Maths

Calculate the difference when information is presented in a bar chart

Calculating within 20

Unit Summary

In this unit pupils will add 3 addends. They will use a strategy such as finding 2 addends to total 10 or 2 numbers to bridge though 10.

Lesson Summary

You will learn to calculate the difference when information is presented in a bar chart.

Key Notes

  • A bar chart is a graph that uses bars to represent information.
  • Bar charts can have different scales.
  • The difference is one of the parts that make the whole. Whole - part = part (difference)
  • You can calculate the difference by counting on from the known part to the whole.

Vocabulary To Learn

  • Bar chart: A graph that uses bars of different heights to represent information.
  • Difference: The result of subtracting one number from another. Way in which two or more things we are comparing are not the same.
  • Counting on: A mental strategy used to add numbers.
  • Subtraction: To partition one part from another (the subtrahend from the difference), or to decrease an amount by taking an amount away.

Common Mistakes To Avoid

  • Children may initially struggle to read and interpret the data on the bar chart / graph.

3 Quick Questions (With Answers)

1. Solve this in steps: explain the method from this lesson and why each step matters.

A bar chart is a graph that uses bars to represent information. Bar charts can have different scales.

2. Use this key word in a maths sentence and explain it clearly. 'Bar chart'

A graph that uses bars of different heights to represent information. Use this word when showing your method, then check your final answer is reasonable.

3. Spot and fix this common maths mistake.

Mistake: Children may initially struggle to read and interpret the data on the bar chart / graph. Correction: A ruler can be used to help children line up the top of the bar with the scale. Model this as a strategy to support accurate reading.

More Lessons In This Unit

Browse all guides in the Year 2 Maths guide library.