Measuring Length — Year 1 Lesson Plan
National Curriculum: Mathematics — Measurement: compare, describe and solve practical problems for lengths and heights, Year 1
Overview
Pupils learn to compare, describe, and measure lengths using non-standard units and then standard units (cm). They explore the language of length and distance, and develop an understanding of what it means to measure accurately, including the importance of starting at zero.
Learning Objectives
- Compare lengths using the language: longer, shorter, taller, the same.
- Measure lengths using non-standard units (e.g. cubes, hands).
- Measure lengths in centimetres using a ruler.
- Understand the importance of starting at zero when measuring.
Key Vocabulary
Suggested Lesson Structure
Hold up two pencils of clearly different lengths. Ask: which is longer? How do you know? Can we say by how much? Establish the need for measuring.
Measure a book using cubes — count how many cubes long it is. Discuss limitations: cubes must be the same size, no gaps. Introduce the centimetre as a standard unit. Model using a ruler: line up the zero, read the number the end reaches.
Pupils measure a set of objects first with cubes, then with a ruler. Record both. Discuss: why did the ruler give the same answer for everyone, but the cube count might differ?
Pupils estimate and then measure five objects in the classroom using a ruler. Record estimate and actual measurement. Discuss: which estimates were closest?
A ruler is placed with the object starting at 2 cm rather than 0 cm. Ask: what is wrong? What would the correct measurement be?
Common Misconceptions
- Not starting from zero — pupils often start from the 1 cm mark. Explicitly model starting at zero every time.
- Placing gaps between non-standard units when measuring — demonstrate that units must be placed end to end with no gaps.
Prior Knowledge
Pupils should already be able to:
- Experience comparing lengths informally in EYFS.
- Ability to count objects reliably.
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