Formalising understanding of triangles from KS2
I can classify triangles and know their relevant properties.
Formalising understanding of triangles from KS2
I can classify triangles and know their relevant properties.
These resources will be removed by end of Summer Term 2025.
Lesson details
Key learning points
- An equilateral triangle is a regular triangle and has particular properties.
- A scalene triangle has specific properties.
- An isosceles triangle has properties including a line of symmetry that splits it into two congruent triangles.
- A right-angled triangle can be scalene or isosceles.
Keywords
Equilateral - Equilateral triangles have three equal-sized angles and three edges of equal length. They are regular triangles.
Scalene - Scalene triangles have three different-sized angles and three different-sized edges (sides).
Isosceles - Isosceles triangles have two equal-sized angles and two sides of the same length.
Right-angled triangle - A right-angled triangle has exactly one 90° interior angle.
Common misconception
The horizontal side length of an isosceles triangle is always the base side.
The base side of an isosceles triangle can have any orientation. It is important to look at the hash marks, angle markers, or measurements.
To help you plan your year 8 maths lesson on: Formalising understanding of triangles from KS2, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your year 8 maths lesson on: Formalising understanding of triangles from KS2, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 3 maths lessons from the Geometrical properties: polygons unit, dive into the full secondary maths curriculum, or learn more about lesson planning.
Licence
Starter quiz
6 Questions






$$f$$° -
155°
$$g$$° -
25°
$$h$$° -
65°
right angle -
90°
not an angle on the diagram -
45°
sum of angles on the diagram -
360°
Exit quiz
6 Questions



isosceles -
another angle of 30° and one of 120°
scalene -
one angle of 77° and another 73°
right-angled scalene -
an angle of 60° and one of 90°
equilateral -
impossible to have this triangle with an angle of 30°