New
New
Year 1

# Estimate length in cm

I can estimate the length of different objects by using known lengths.

New
New
Year 1

# Estimate length in cm

I can estimate the length of different objects by using known lengths.

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## Lesson details

### Key learning points

1. Length can be estimated in the same way you estimate a position on a number line.
2. The width of your fingernail is about 1 cm in length.
3. The distance from the end of your thumb to the side of your hand is about 10 cm in length.

### Common misconception

Children may think that they need to get a ruler and measure length before they can estimate it.

Reinforce the language of 'about' to show that estimates do not need to be exact. Use known lengths to support estimating within 10cm, for example, practical objects such as paperclips or buttons which are about 1cm in length.

### Keywords

• Estimate - To find a value that is close enough to the right answer, usually with some careful thought involved.

• About - Something may not be an exact measurement, but it is close to it.

You could adapt or add to the known lengths used in this lesson to include those which children will be familiar with from within their immediate environment.
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).

## Starter quiz

### 6 Questions

Q1.
What is the length of this pencil? cm.
Q2.
What is the height of this plant? cm.
Q3.
What number is missing from this number line?
Q4.
Estimate which number the arrow is pointing to.
7
8
Q5.
Estimate which number the arrow is pointing to.
14
16
Q6.
Jun has made 13 using 10 and a bit. What is the missing number in this picture?

## Exit quiz

### 6 Questions

Q1.
Which object measures about 1 cm?
An eraser
A glue stick
Q2.
Which object measures about 10 cm?
A button
Q3.
Which is the best estimate for the length of this playdough shape?
4 cm
5 cm