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

Starter quiz

Which representation matches the number on the chart correctly?
What do you notice about all of these numbers? 66 65 64 63

They are all odd numbers.

They all have the same ones digit.

They all have the same tens digit. ✓
Which one hundred square is representing 3 rows of ten and 2 more ones?
Which description matches the one hundred square?

9 rows of ten and 4 more ones.

4 rows of ten and 9 more ones. ✓

49 rows of ten.
Jun has these Base 10 blocks. Which of these numbers could he make using them?

33

21 ✓

12 ✓

14
Laura has these Base 10 blocks. Which of these numbers could she make using them?

69

43 ✓

20 ✓

82

Exit quiz

What is the previous multiple of 10?

30

40 ✓

50
What is the next multiple of 10?

'80' ✓
Which shows 46?

A

B

C ✓
Which number has a ones digit larger than the tens digit?

A

B

C ✓
The top line represents 100 Use this line to estimate the length of the other line

I think it is about 20

I think it is about 60 ✓

I think it is about 90
The top line represents 100 Which line matches this estimate? "I think it is about 35"

A

B

C ✓

Worksheet

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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.