Primary 5 Maths | Area and Perimeter: Tutor Prep Guide | 45 minutes from counting squares to composite shapes

2026-11-08

Tutor lesson-prep guides · Primary Maths

For one and the same rectangle, perimeter is how much fence goes round it and area is how many tiles cover it. The two numbers often look similar, so pupils grab the wrong formula. Separate them with the fence and the tiles from the first minute and that error stops happening.

Objectives — Pupils can: (1) explain that perimeter is the total length of the boundary and area is the space covered, and give the unit for each; (2) use length x width and side x side for rectangles and squares; (3) find the area of an L-shape by splitting it or subtracting the missing part; (4) convert between square metres and square centimetres (1 square metre = 10000 square centimetres).

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Column multiplication	25 x 4	100
Length units	How many centimetres in a metre	100
Properties of a square	What is true of all four sides	They are equal
Subtraction	40 – 6	34

02 Lesson flow (45 minutes)

Time	Stage	Tutor does	Student does
0–9 min	Starter: fence and tiles	On a desk: run a finger round the edge for perimeter, sweep the palm across for area	States both meanings and units
9–18 min	Counting squares	On squared paper count the squares inside a 4 by 3 rectangle, then count the edge squares	Area 12 squares, perimeter 14 units
18–27 min	Formulas come from counting	Let the counting produce length x width, then the four sides produce 2 x (length + width)	Explains why each formula works
27–36 min	Composite shapes	Model an L-shape: 8 x 5 rectangle minus a 3 x 2 corner	Gets 34 square centimetres
36–43 min	Unit conversion	Derive 1 square metre = 10000 square centimetres from 100 x 100	Explains why it is 10000, not 100
43–45 min	Exit check	Three quick oral questions	Answers independently

03 Teaching script (read it out)

Scene 1: Separate the two measures with real objects

The commonest error is not a miscalculation but a wrong choice: asked for area, the pupil computes perimeter. Use two images that cannot be confused: a fence going round (perimeter, in centimetres) and tiles covering (area, in square centimetres).
Before every question ask the pupil to say “fence or tiles”. It takes two seconds and blocks half the lost marks.

Pupil says: “fence or tiles” before starting each question.

Scene 2: Derive the formula by counting

Told to memorise length x width, pupils misuse it on decimals and composite shapes. Count once on squared paper: four rows of three is twelve squares, which is 4 x 3, and the formula has a source.
Do the same for perimeter: count the edge units, the four sides add to 14, which is 2 x (4 + 3). Once they have counted it themselves, the formula stops being a spell.

Pupil does: count once on squared paper and point at which number the formula uses.

Scene 3: Split or subtract composite shapes, never guess

Faced with an L-shape, pupils multiply the longest side by the longest side and the answer comes out too big. Teach both routes: split into two rectangles and add, or take the whole rectangle and subtract the missing corner. Try both, because some shapes split easily and others subtract easily.
Check by estimating a bound first: the area must be less than the 40 of the outer rectangle. An answer outside the bound is instantly wrong.

Pupil does: draw the splitting line or the outer rectangle, and state an estimated range.

04 Question types and worked steps

Type	Example	Steps	Answer
Counting squares	A 4 by 3 rectangle on squared paper	Count squares for area, edge units for perimeter	Area 12 sq cm, perimeter 14 cm
Rectangle formulas	Length 8 cm, width 5 cm	Area length x width, perimeter 2 x (length + width)	Area 40 sq cm, perimeter 26 cm
Square	Side 6 cm	Area side x side, perimeter 4 x side	Area 36 sq cm, perimeter 24 cm
Composite shape	An 8 by 5 rectangle with a 3 by 2 corner removed	Subtract or split, then check against the bound	34 sq cm

Sanity check (teach this): Reasonableness checks: area units always carry the word square; perimeter units are plain lengths; a larger area number does not have to beat the perimeter number for the same shape; a composite area is always less than its outer rectangle; 1 square metre is 10000 square centimetres, not 100; the parts of a split add back to the whole; every answer can be labelled fence or tiles.

05 Independent practice (3 questions)

Question	Answer	What to watch
5 formula questions	Three rectangles, two squares, each asking for area and perimeter	Checks the two formulas and units are not mixed
4 composite shapes	Two by splitting, two by subtracting, one with two corners missing	Checks a splitting line is drawn
3 conversion questions	Square metres to square centimetres and back	Checks 10000 is used

06 Common mistakes and what to say

Mistake	Student writes	Say this
Area and perimeter swapped	Asked for area, computes 2 x (8 + 5)	“Fence or tiles? Tiles cover the inside, they do not go round the edge.”
Area written in centimetres	Answering 40 cm for an area	“What did you cover? Square centimetres, not centimetres.”
Longest sides multiplied on an L-shape	Straight to 8 x 5 = 40	“40 is the whole outer rectangle. You have not removed the corner yet.”
Treating a square metre as 100 square centimetres	Answering 100 sq cm	“A metre is 100 cm, so the square is 100 by 100, and the area is 100 x 100.”

07 Homework (paper, section and question numbers)

Primary 1 to 6 Maths test papers with answers — Do the P5 area and perimeter questions, writing fence or tiles first
Primary Maths chapter index — All chapters in the subject
Redo this chapter — Redo four composite shapes, two by splitting and two by subtracting

08 Exit check (last 5 minutes)

Question	Answer	Decision
What is the difference between area and perimeter	Perimeter goes round, area covers the surface	Silence means back to the second stage
What marks out a unit of area	The word square	Saying centimetres means back to the third stage
How can an L-shape area be found	Split and add, or subtract from the whole	Saying multiply the longest sides means back to the fifth stage
How many square centimetres in a square metre	10000	Answering 100 means back to the sixth stage

09 Tutor FAQ

Should triangle area come first?

No. Secure rectangles, squares and composite shapes first; the triangle and parallelogram formulas rest on the same splitting idea.

A pupil counts squares very slowly

Allow the slowness but insist they say “four rows of three” afterwards, so counting turns into multiplication instead of staying one-by-one.

Why is a square metre not 100 square centimetres?

Because both dimensions convert: a square of side 100 cm has area 100 x 100. Show it once on squared paper and the point lands.

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A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.