Area and Perimeter — Year 4 Lesson Plan
National Curriculum: Mathematics — Measurement: calculate and compare the area of rectangles (including squares), and including using standard units, Year 4
Overview
Pupils learn to calculate the perimeter of rectilinear shapes and find the area of rectangles and rectilinear shapes by counting squares and using the formula length × width. They explore the relationship between area and perimeter and discover that shapes with the same area can have different perimeters.
Learning Objectives
- Calculate the perimeter of rectilinear shapes by adding all side lengths.
- Find the area of rectangles using the formula length × width.
- Calculate the area of rectilinear shapes by counting squares or decomposing.
- Understand that area and perimeter are independent measurements.
Key Vocabulary
Suggested Lesson Structure
Show two different rectangles on squared paper. Ask: which has a bigger border? Which covers more space? Introduce the words perimeter and area as names for these two ideas.
Model calculating perimeter by adding all sides, then by using 2(l + w) for rectangles. Model area by counting squares, then introduce length × width. Show a rectilinear shape and demonstrate how to split it into rectangles to find total area.
Pupils calculate perimeter and area for a set of shapes on squared paper. Include rectangles and L-shapes. Discuss: can two shapes have the same area but different perimeters?
Pupils find all rectangles with an area of 24 cm² and record their perimeters. Apply: a garden has an area of 30 m² — give two possible sets of dimensions.
True or false: if a shape has a bigger perimeter, it must have a bigger area. Pupils give a counter-example.
Common Misconceptions
- Pupils confuse area and perimeter — use consistent language and always clarify which is being measured.
- Adding only two sides of a rectangle rather than all four for perimeter.
- Thinking larger perimeter = larger area — explicitly challenge with counter-examples.
Prior Knowledge
Pupils should already be able to:
- Ability to measure lengths in cm and m.
- Knowledge of multiplication facts.
- Familiarity with 2D shapes and right angles.
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