Mathematics · Year 1 · Measurement and Comparison · Spring Term

Comparing Lengths and Heights

Comparing the size of objects using direct comparison and language like 'longer', 'shorter', 'taller'.

• National Curriculum Attainment Targets
• KS1: Mathematics - Measurement

About This Topic

Length and height in Year 1 involve students moving from subjective descriptions (like 'big' or 'small') to objective comparisons and measurements. The National Curriculum requires pupils to compare, describe, and solve practical problems for lengths and heights (e.g., long/short, longer/shorter, tall/short, double/half). They also begin to measure using non-standard units, such as paperclips, cubes, or handspans.

This topic introduces the concept of a 'unit' of measurement. Students learn that to compare two things fairly, they must start from the same baseline and use consistent units without gaps or overlaps. This is a vital precursor to using rulers and standard units like centimeters. This topic comes alive when students can physically model the patterns by measuring their own height, classroom furniture, and playground equipment.

Key Questions

1. Analyze how we know which object is longer if they don't start at the same place?
2. Explain why we must use the same sized unit when measuring the length of two different things?
3. Differentiate between length and height.

Learning Objectives

• Compare the lengths and heights of two objects using direct comparison and standard comparative language.
• Explain how to compare lengths and heights fairly when objects are not aligned.
• Classify objects as longer, shorter, taller, or shorter based on visual comparison.
• Demonstrate the use of non-standard units to measure and compare lengths.

Before You Start

Sorting and Classifying Objects

Why: Students need to be able to group objects based on observable properties before they can compare specific attributes like length and height.

Basic Shape Recognition

Why: Identifying common shapes helps students focus on the dimensions of objects rather than their overall form.

Key Vocabulary

longer	Describes something that has more length than something else.
shorter	Describes something that has less length than something else.
taller	Describes something that has more height than something else.
height	How tall something is, measured from bottom to top.
length	How long something is, measured from end to end.

Watch Out for These Misconceptions

Common Misconception

Starting from different points

What to Teach Instead

Students often compare two objects without aligning their bases. Use a 'starting line' (like a piece of tape) and insist that all objects being measured or compared must touch that line to be fair.

Common Misconception

Leaving gaps between units

What to Teach Instead

When measuring with cubes or paperclips, children often leave spaces between them. Show how gaps make the measurement 'shorter' than it really is, emphasizing that units must touch 'end-to-end'.

Active Learning Ideas

Inquiry Circle: The Great Cube Measure

Groups choose five items in the classroom and measure them using Unifix cubes. They must record their results and then order the items from shortest to longest on a large piece of sugar paper.

20 min·Small Groups

Think-Pair-Share: Body Part Units

Pairs measure the width of their desk using their handspans. They compare their results and discuss why one student might have '6 hands' while the other has '7 hands' for the same desk.

15 min·Pairs

Gallery Walk: Height Chart

Students mark their height on a long strip of paper on the wall. They then walk along the 'chart' to find someone who is 'taller than' them and someone who is 'shorter than' them, using the correct vocabulary.

15 min·Whole Class

Real-World Connections

• Builders compare the lengths of beams and the heights of walls to ensure structures are built to specification, using measuring tapes to check their work.
• Clothing designers compare the lengths of sleeves and the heights of models to create garments that fit correctly, using fabric and patterns as their units of measure.
• Parents compare the heights of their children against growth charts to monitor development, noting how much taller they are getting each year.

Assessment Ideas

Exit Ticket

Provide students with two pencils of different lengths, one slightly shorter and one significantly longer. Ask them to write one sentence comparing their lengths using the words 'longer' or 'shorter'.

Quick Check

Place three classroom objects (e.g., a book, a crayon, a ruler) on a table, not aligned at the base. Ask students to point to the tallest object and explain how they know, encouraging them to describe the process of visual comparison.

Discussion Prompt

Show students two strings of different lengths that do not start at the same point. Ask: 'How can we be sure which string is longer? What do we need to do?' Guide them to discuss aligning the ends.

Frequently Asked Questions

What are non-standard units?

Non-standard units are everyday objects used to measure something, such as cubes, paperclips, or footsteps. They are used in Year 1 to help children understand the process of measuring before they are introduced to the complexities of standard units like centimeters.

How can active learning help students understand length?

Active learning allows students to physically interact with the objects they are measuring. By moving around the room and using different items as units, they discover the 'rules' of measurement for themselves, such as the need for no gaps. Collaborative tasks also encourage them to use comparative language (longer, shorter, tallest) in a real-world context, which is more effective than just looking at pictures.

Why is height different from length?

Height is a measure of how 'tall' something is vertically (up and down), while length is how 'long' something is horizontally (side to side). In Year 1, we use both terms to help children describe objects in different orientations.

How can I help my child measure at home?

Ask them to find out how many 'spoon lengths' long the kitchen table is. Then ask them to guess how many 'fork lengths' it will be. This helps them understand that the size of the unit changes the final count.