Year 1 - Maths
Estimate length in cm
Numbers 0 to 20 in different contexts
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will consolidate their counting to 20. They will measure objects using non-standard and standard measures and record outcomes, providing a context for counting and comparing numbers to 20.
Lesson Summary
You will learn to estimate the length of different objects by using known lengths.
Key Notes
- Length can be estimated in the same way you estimate a position on a number line.
- The width of your fingernail is about 1 cm in length.
- The distance from the end of your thumb to the side of your hand is about 10 cm in length.
Vocabulary To Learn
- 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.
Common Mistakes To Avoid
- Children may think that they need to get a ruler and measure length before they can estimate it.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Length can be estimated in the same way you estimate a position on a number line. The width of your fingernail is about 1 cm in length.
2. Use this key word in a maths sentence and explain it clearly. 'Estimate'
To find a value that is close enough to the right answer, usually with some careful thought involved. 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 think that they need to get a ruler and measure length before they can estimate it. Correction: 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.
More Lessons In This Unit
- Comparing lengths Study Guide
- Estimate and measure length and record results in a table Study Guide
- Measure items using centimetre cubes and record results in a table Study Guide
- Measure length using a ruler Study Guide
- Measure length using centimetre cubes Study Guide
- Measure length using objects Study Guide
- Measure length using objects and record results in a table Study Guide
- Solve addition and subtraction problems involving length Study Guide
- Solve problems by measuring different lengths in cm using a ruler Study Guide
Browse all guides in the Year 1 Maths guide library.