Make and draw triangles on circular geoboards | Maths

Starter quiz

Match the shape name to the number of vertices it has.
- Trapezium
  
  ⇔
  
  4 vertices ✓
- Hexagon
  
  ⇔
  
  6 vertices ✓
- Decagon
  
  ⇔
  
  10 vertices ✓
Tick the shape which is a trapezium.
True or false? These lines are parallel to one another.
- True ✓
- False
Complete the sentence. This polygon has ______ pair(s) of parallel sides.
- '1' ✓
The pentagon has been decomposed into two polygons which have the same name. What is the name of the polygon?
- 'quadrilateral' ✓
Complete the sentence. A pair of ______ sides meet to make a right angle.
- 'perpendicular' ✓

Exit quiz

Complete the sentence. This is a triangle and it has ______ vertices.
- '3' ✓
True or false: Alex has drawn a pair of perpendicular lines on this circular geoboard.
- True
- False ✓
Complete the sentence. This is a triangle and it has ______ pair(s) of perpendicular sides.
- '0' ✓
Complete the sentence. This is a triangle and it has ______ pair(s) of perpendicular sides.
- '1' ✓
Select the statements that are true for this polygon drawn on a circular geoboard.
- It is a triangle. ✓
- It is a quadrilateral.
- It has one pair of perpendicular sides.
- It has three equal sides. ✓
- It has one pair of parallel sides.
Select the vertices that could be joined to form a right-angled triangle.
- a, b and c
- a, d and e ✓
- b, d and e

Worksheet

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Presentation

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Lesson Details

Key learning points

Three points on a geoboard can be joined to make a triangle.
Triangles can have different properties.
Different triangles can be created on the same geoboard.

Common misconception

Pupils may overgeneralise about the way a triangle should look e.g. not recognising a scalene triangle as a triangle.

Throughout the lesson, model different triangles in different orientations. Ensure pupils see boundary examples such as scalene triangles with one very small acute angle, or long and thin isosceles triangles.

Keywords

Vertex / vertices - A vertex is the point where two lines meet. The plural is vertices.
Perpendicular - Two lines which meet at a right angle are perpendicular.