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.
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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.
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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
Prior knowledge starter quiz
6 Questions
Q1.TU is a line segment. $$a$$° = °.

Q2.These three angles lie around a point on a full turn. $$b$$° = °.

Q3.This diagram shows four angles around two line segments that meet at an intersection. Which of these statements are correct for angle $$c$$°?

Q4.This diagram shows four angles around two line segments that meet at an intersection. Which of these statements are correct for angle $$d$$?

Q5.PQ and RS are straight line segments. $$e$$° = °.

Q6.PQ and RS are straight line segments. Match each angle to its size.

$$f$$° -
155°
$$g$$° -
25°
$$h$$° -
65°
right angle -
90°
not an angle on the diagram -
45°
sum of angles on the diagram -
360°
Assessment exit quiz
6 Questions
Q1.Which of these statements are true about this triangle?

Q2.This triangle is scalene. Which of these are possible values of $$b$$?

Q3.Which of these statements are correct for this triangle?

Q4.An equilateral triangle has one side of length 40 cm. Which of these statements are correct?
Q5.An isosceles triangle has an angle of 90°, and a side of length 19 cm. What is the size of one of its other angles, in degrees? °.
Q6.Three different triangles each have an angle of 30°. Match the name of each triangle to their possible angles.
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°