Classifying triangles by sides (equilateral, isosceles, scalene) and by angles (right-angled, acute, obtuse).
Where your child meets this in real life: Identifying triangle types in structures, art, and design
Each SEAG paper has 28 maths questions. Questions 29 to 50 are multiple choice with five possible answers, and questions 51 to 56 need a short written answer. With 56 questions in 60 minutes across English and maths, that is about a minute per question.
SEAGReady breaks classify triangles into 3 steps, taught in order so each skill builds on the last.
Classify triangles as equilateral, isosceles, or scalene based on the number of equal sides
Classify triangles as right-angled, acute, or obtuse based on their largest angle
Describe triangles using both side and angle classifications together (e.g., 'right-angled isosceles')
Try three free questions from our classify triangles course. They start easy and get harder, so you can see where your child's confidence runs out. If they manage the last one without a hint, this topic is probably secure. If not, the steps above show where to start.
The triangle shown has side lengths 9 cm, 9 cm and 13 cm. What type is it when classified by side lengths?
Every angle in the triangle shown is 60°. What type of triangle is it by angles?
Triangle P has exactly two equal sides and angles 50°, 50° and 80°. Triangle Q has three different sides and angles 37°, 53° and 90°. Triangle R has three different sides and angles 30°, 42° and 108°. Which is acute isosceles?
This is the exact interactive worked example your child sees in SEAGReady. Step through it and watch the method build up.
Lucy is sorting triangular tiles for an art project. One tile has sides measuring 5 cm, 5 cm, and 8 cm.
What type of triangle is this tile?
5 cm, 5 cm, 8 cm
Look at the three side lengths: 5 cm, 5 cm, and 8 cm
Step 1 of 3
Lucy is sorting triangular tiles for an art project. One tile has sides measuring 5 cm, 5 cm, and 8 cm.
What type of triangle is this tile?
The tile is an isosceles triangle because it has exactly 2 equal sides.
The key insight: Count the matching sides: 3 equal = equilateral, 2 equal = isosceles, 0 equal = scalene!
Common mix-up: Calling it equilateral because two sides match. Equilateral means ALL three sides are equal, not just two.
These are the misconceptions we see most often in classify triangles, including the ones our practice questions are specifically designed to catch.
Struggling with classify triangles? The real gap is often in one of these earlier topics.
Sitting the SEAG test this November? Read our last-month revision plan, Paper 1 vs Paper 2 and test day guide.
SEAGReady finds the exact step where your child gets stuck, teaches it with worked examples like the one above, and brings it back for review so it sticks.
Free to start · no card needed