Topics · Shapes & Measurement
Triangles and shapes
Build triangles from rules, and spot shapes that match exactly.
A shape's rules decide what it can be.
More ways into this idea
- Play with itAngle LabSwing two angles as far as they go — the third answers
- Make it a gameTriangle ForgeForge triangles to order — or prove the order impossible
- Test yourselfA fresh mixed set, whenever you likeExplanations after every question. Nothing is recorded.
Common sticking points
- A common sticking point is classifying a triangle by how it LOOKS on the page. The names come from measured sides and angles — a tilted equilateral is still equilateral.
- Another is thinking same angles means an exact copy. Same three angles only fix the SHAPE — a mini version sneaks through. An exact copy needs the sides too.
- The three inside angles always total 180°. If two angles are known, the third is forced — no measuring needed.
Try this together
Draw any triangle, tear off its three corners, and slide them together point-to-point. They always make a straight line — 180°. Try it with a wildly different triangle. Same line!
1–5 minutes, no materials to buy, nothing to hand in.
Ontario curriculum details
- E1.1Know triangle properties and construct triangles
- E1.2Identify and build congruent shapes
Plain-language summaries. See the full curriculum for every expectation and the official source.