Mathematics

Advanced

50 mins

Teacher/Student led

Learning Goals

Learning Outcomes

Lesson Files

+65 XP

Teacher-led from the board — pupils need no device

What you need:
IWB/Projector/Large Screen

Enlargement and Scale Factor

Learn how to enlarge shapes by multiplying each side by a scale factor, keeping the same proportions. Discover how to find the scale factor from an original and its enlarged image.

Warning: Your screen size is quite small for viewing this. Rotate your device into landscape mode if you can.

1 Getting Started
2 Watch and Notice
3 Try It Together
4 Draw the Enlargement in Your Copy
5 Class Challenge
Pupil practice

Your turn

Your teacher is running this lesson on the board. Here is the part you can try yourself.

Your written work is on page 89

Transformation playground

1 - Getting Started ~5 mins

A 3 by 2 rectangle beside a 6 by 4 rectangle, the same shape at twice the size

Here is a small rectangle on the board, and beside it a bigger copy of exactly the same shape.

What got bigger? And by how much? Roughly how many times taller and wider is the second one?

👇 Mark your steps as done as you complete them.

+5 XP

2 - Watch and Notice ~9 mins

Watch these shapes on the grid, each with its enlargement drawn beside it. Look at the sides of each copy compared to the original.

A side of 3 squares becomes 6 when we multiply by 2 — not 5, as if we added 2. That multiplier is the scale factor: the number we multiply every side by.

The copy keeps its proportions. That means it stays the same shape: the angles do not change and every side grows together, so it is never squashed or stretched.

👇 Mark your steps as done as you complete them.

+10 XP

3 - Try It Together ~10 mins

Key point

Today we work through these enlargements together on the board. We start with a rectangle and enlarge it by a scale factor of 2, then the same shape by 3. Then we take a triangle and enlarge it by 2, and finally by 4 — and each time we check every side against the original before we agree.

Enlarge and check the sides

+15 XP

4 - Draw the Enlargement in Your Copy ~5 mins

COPYBOOK MOMENT

In your maths copy, draw a rectangle that is 2 cm by 3 cm. Then draw its enlargement by scale factor 3 beside it.

Label the new side lengths. Check each one by multiplying the original length by the scale factor.

+10 XP

5 - Class Challenge ~9 mins

Key point

Today we work through these enlargements together, each one a step harder. First, enlarge the rectangle by scale factor 2 to match the dashed outline. Then enlarge the triangle by 3. Then enlarge the L-shape by 2.

Before the last jump, we flip the skill and find a scale factor from two lengths. An original side measures 2 squares and the matching side on the image measures 8 squares. Divide image length by original length: 8 ÷ 2 = 4. The scale factor is 4. Check a second pair of sides the same way so every length agrees.

Then finish with the final challenge: enlarge the triangle by scale factor 4 to match the copy that is four times the size.

Match the enlargement

+15 XP

Pupil practice

Module 8 · Location, Transformations and Scale Shape & Space

Lesson 96 · Enlargement and Scale Factor

Download Activity Book page (PDF)

123learn · Online learning platform

Unlock the full learning experience

You're previewing this lesson. Get full access to this lesson and hundreds more — each one ready to teach, with interactive activities, printable resources and pupil progress tracking built in.

Hundreds of curriculum-aligned lessons

Interactive activities in every lesson

Printable resources & progress tracking

Get started

Copyright Notice
This lesson is copyright of 123Learn.ie 2017 - 2025. Unauthorised use, copying or distribution is not allowed.