Build · Drag
Fence Builder
Drag fence pieces around the garden to build an animal pen. Watch the fence counter tick up — that's the perimeter! Then take on challenges like "build a pen with perimeter exactly 24 m".
Maths · Ages 8–10 · Free
How far is it all the way around?
Perimeter is the distance around a shape — and the best way to learn it is to play with it. Walk it, build it, quiz it, solve it.
Free interactive lessons and three friendly games. No downloads, no accounts, no ads — English and 繁體中文.
The Games
Pick a Game and Start Playing
Three small games — understand it, get fast at it, then reason backwards with it.
Quiz · Beat the clock
Perimeter Quiz Rush
A labelled shape pops up — pick the right perimeter before the timer runs out! Six levels, from squares to tricky irregular shapes. Streaks, stars and confetti included.
Puzzle · Work backwards
Shape Detective
The perimeter is known… but one side is missing! Detectives work backwards: perimeter minus the known sides. Twelve cases to close, from rectangles to irregular shapes.
Why It Works
Fun First, Learning Built In
See it
Interactive lessons where kids walk, slide and tick off the edges — perimeter stops being a formula and becomes something you can see.
Build it
Fence Builder lets kids drag real fence pieces and watch the metres add up — learning by doing, not memorising.
Quiz it
Quiz Rush and Shape Detective turn practice into a game kids ask to play again — with gentle feedback that shows the working out.
For Parents & Teachers
Free perimeter practice for primary school kids
What is perimeter?
Perimeter is the distance all the way around a shape. For primary students in grades 3–4 it's usually the first geometry-measurement idea they meet: add up every side and you have the perimeter. This site breaks it into six tiny lessons — what perimeter means, squares and rectangles, triangles and polygons, irregular shapes, working backwards to a missing side, and perimeter in real life.
Games that practise the real skill
Every game targets one part of the skill. Fence Builder builds the concept, Quiz Rush builds fluency with whole-number sides in centimetres and metres, and Shape Detective teaches the reverse reasoning found in exam questions: perimeter minus the known sides equals the missing side.
- Fence Builder — drag & drop pens, 12 challenges, exact-perimeter goals.
- Perimeter Quiz Rush — 6 levels, 3 lives, beat-the-clock multiple choice.
- Shape Detective — 12 missing-side cases with hints and step-by-step strategy.
Safe and simple
Everything runs in the browser — on a computer, tablet or phone. No downloads, no accounts, no ads. Progress and stars are saved on the device only, and every page works in English and 繁體中文.