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).

Video

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6 Questions

Q1.
What is the length of this pencil? cm.
An image in a quiz
Correct Answer: 13, 13 cm
Q2.
What is the height of this plant? cm.
An image in a quiz
Correct Answer: 11, 11 cm
Q3.
What number is missing from this number line?
An image in a quiz
Correct Answer: 14
Q4.
Estimate which number the arrow is pointing to.
An image in a quiz
Correct answer: 6
7
8
Q5.
Estimate which number the arrow is pointing to.
An image in a quiz
Correct answer: 12
14
16
Q6.
Jun has made 13 using 10 and a bit. What is the missing number in this picture?
An image in a quiz
Correct Answer: 3, three

6 Questions

Q1.
Which object measures about 1 cm?
An eraser
A glue stick
Correct answer: A paperclip
Q2.
Which object measures about 10 cm?
Correct answer: A lollipop stick
A button
A ladybird
Q3.
Which is the best estimate for the length of this playdough shape?
An image in a quiz
4 cm
5 cm
Correct answer: 6 cm
Q4.
Which example has used '5 and a bit' correctly to estimate the length of this playdough snake?
An image in a quiz
I estimate that this snake is about 7 cm long because 5 and 2 is equal to 7
Correct answer: I estimate that this snake is about 9 cm long because 5 and 4 is equal to 9
Q5.
I think that a good estimate for the length of this block is cm.
An image in a quiz
Correct Answer: 7, 7 cm
Q6.
I think that a good estimate for the length of this leaf is cm.
An image in a quiz
Correct Answer: 8, 8 cm