Use a number line to position and estimate the numbers 20-99

I can position the numbers 20-99 on a number line including in the context of measures.

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Year 2

Use a number line to position and estimate the numbers 20-99

I can position the numbers 20-99 on a number line including in the context of measures.

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Share activities with pupils

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Lesson details

Key learning points

We can use the intervals on a number line to help us find and position other numbers.
The multiples of ten can help us find which decade a number is in.
The midpoint we refer to is halfway between each multiple of ten.
The midpoint we refer to has a ones digit of five.
The midpoint can help us position numbers that are not close to a multiple of ten.

Common misconception

When finding the previous multiple of ten, children may misapply what they know about counting in tens. For example, they may think 30 is before 40, so think 30 is the multiple of ten before 45

Make deliberate errors to discuss and encourage children to visualise, then label, their own number lines marked in tens.

Keywords

Midpoint - The middle of something. The point halfway along.
Previous - Going before in time or order.

When referring to multiples of ten, avoid the language of 'the multiple of ten that is more/less' and instead use 'previous' and 'next' to not confuse with the idea of ten more and ten less. Tap numbers on the Gattegno chart to support with positioning on the number line.

Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).