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MathematicsGeometryAges 12–14

Similarity and enlargement

Understand similarity as a relationship where one shape is an enlargement of another; construct similar shapes by enlargement with a given scale factor and centre, with and without coordinate grids

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Similarity and enlargement means practising the idea at the table with counters or paper models and one clear check. We will demo once, then your child tries.

Materials: Paper shapes or a ruler and pencil; Shape or angle name cards. 1. Say the goal of Similarity and enlargement in plain words once. 2. Adult traces or shows one shape/angle and names a key property. 3. Child measures or classifies three shapes/angles and names a property each time. 4. Fresh check: one fresh property name. Record and stop. Done: three correct property names with a sketch or measure. Proof: parent note of examples and results. Stop: End after the fresh check; keep optional challenge for another day.

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Similarity and enlargement practice

Practice key ideas from Similarity and enlargement.

Free · no login · no ads · Practice answers and completion are not saved. Parent observation remains the lesson record.

Learning resources

Extra practice links — they do not replace Gakuva’s teaching approach.

PhET Interactive Simulations · Practice link — not the full lesson

Area Builder

Open practice (new tab)
Before you open · source notes

Area Builder supports hands-on exploration for Similarity and enlargement. Not every lab worksheet.

Free interactive page, no sign-in required for the tested path.

Before you open

Ask the learner what they changed in the sim or page and what they observed.

Opening this link does not save learning or assess mastery.

Source, access and review notes

Public PhET Interactive Simulations page. An anonymous GET on 2026-11-12 returned HTTP 200 with no login or payment prompt for this URL. Opening the link does not save practice or assess mastery. An adult should preview and guide the learner.

PhET Interactive Simulations. “Area Builder.” External page; Gakuva does not copy, host, embed, or redistribute materials.

Unknown — link only

Check understanding

  • Enlarge a shape by a given scale factor from a specified centre of enlargement
  • Determine the scale factor between two similar shapes by comparing corresponding sides
  • Explain why corresponding angles in similar shapes are equal while sides are in proportion
“If your child wants to enlarge a photo so it's three times bigger, can they work out the new dimensions — and explain that the shape stays the same but all lengths increase by the same factor?”

Curriculum record

Type
Conceptual
Subject
Mathematics
Domain
Geometry
Age range
Ages 12–14

Standards

ccss-math:8.G.4the-ontario-curriculum-mathematics-2020:ON-MATH-2020-G7-E1.3uk-nc-2013:KS3.Maths.Geo.9