Area and Perimeter Today

Overview

In this lesson (Lesson 11 of 20), students calculate area and perimeter of simple 2D shapes using familiar metric units and instruments with labelled markings. Students also compare their results and explain what their measurement means.

Learning intentions

• Students will calculate the perimeter of simple shapes by measuring and adding side lengths in centimetres.
• Students will calculate the area of simple shapes by counting square units (1 cm²).
• Students will choose a suitable method (measuring or counting) and check their answers for reasonableness.
• Students will represent their calculations using words, numbers and correct units.

Success criteria

• I can find the perimeter by adding the lengths of all outer sides and stating the unit (cm).
• I can find the area by counting full square units and stating the unit (cm²).
• I can show my working clearly enough for someone else to follow.
• I can check my answer and explain whether it seems reasonable.

Curriculum links

• Measurement — students measure and compare objects using familiar metric units of length, mass and capacity, and instruments with labelled markings.
• Measurement — calculate and compare using units and instruments with labelled markings.

Lesson structure (60 minutes)

1. 0–5 min · Warm-up (Perimeter quick check). Teacher displays two small rectangle shapes with side labels (e.g., 4 cm and 7 cm) and asks: “Which total matches the perimeter?” Students work individually, then discuss with a partner.

2. 5–12 min · Introduction (Area vs perimeter). Teacher draws a 3 cm by 4 cm rectangle, labels side lengths, and separately highlights 1 cm² squares inside it. Students respond to prompts: “Is this perimeter or area? Why?” and record a short definition in their books.

3. 12–22 min · Direct teaching (Model calculating perimeter). Teacher models perimeter step-by-step: write all outer side lengths, add them, and include units (cm). Students follow with a blank template and complete a guided example rectangle (e.g., 2 cm by 6 cm).

4. 22–35 min · Guided practice (Area counting). Teacher distributes grid cards (with 1 cm² squares) showing simple L-shapes and rectangles. Students count only full squares for area, record the number of squares, then write the unit as cm²; teacher circulates for accuracy and unit language.

5. 35–45 min · Consolidation (Perimeter from counting/measurement). Teacher shows one shape where students can either measure side lengths from the grid or count squares along each outer edge. Students choose one method, calculate perimeter (cm), and underline the sides they used so their working is clear.

6. 45–55 min · Independent task (Complete both). Students complete a worksheet with 3 shapes: one rectangle, one composite step shape, and one irregular but grid-based shape. They calculate both perimeter and area, show working, and include units. Teacher uses a quick checklist during circulation.

7. 55–60 min · Exit ticket (Reasoning + units). Teacher gives an exit ticket: “A rectangle is 5 cm by 3 cm. Find perimeter and area.” Students answer and write a one-sentence explanation about how they know the difference between cm and cm².

Resources

• 1 cm grid cards (rectangles and step/L shapes), printed or laminated
• Centimetre ruler with clear markings for checking edge lengths
• Student worksheet: 3 shapes requiring perimeter and area
• Recording sheets with two columns: Perimeter (cm) and Area (cm²)
• Coloured pencils (optional) to shade 1 cm² squares for area counting
• Whiteboard/markers
• Exit ticket slips
• Timer for structured work time

Assessment

• Formative checks during guided practice: teacher listens for correct adding of all outer sides (perimeter) and counting full squares (area).
• Teacher observes student unit use: perimeter answers in cm and area answers in cm².
• Exit ticket: checks both calculations and whether students can justify their method briefly.

Differentiation

• Support:
• Provide sentence starters: “Perimeter is the distance around the outside…” and “Area is the number of square units inside…”
• Offer a partially completed example showing how to label each side length before adding.
• Use laminated grid cards so students can place counters on squares to ensure full-square counting.
• Targeted practice for students who confuse units:
• Quick sort activity: students circle answers that belong to cm vs cm² on a mini-card set (e.g., “14 cm” vs “14 cm²”).
• Extension (for advanced learners):
• Give a shape where area can be found using two parts (split the composite shape) and ask for a second method to verify the answer.
• Challenge: provide two shapes with the same area but different perimeter (or vice versa) and ask students to find both and describe the difference.
• EAL/SEN considerations:
• Use consistent visual models and colour coding (outline outer edge for perimeter; shade interior for area).
• Allow oral explanation in addition to written work; accept diagrams with labels as working.