Students learn to calculate the exterior angles of polygons using clear diagrams and the fact that exterior angles sum to 360°.
The lesson moves from identifying exterior angles to calculating missing angles and finding the number of sides in a regular polygon from a given exterior angle.
Related Blog: Angles in Polygons
Scheme of Work Link
Angles in Parallel Lines and Polygons
Ready-to-teach lesson pack with presentation, worksheet and exam-style practice included with membership.
Differentiated Learning Objectives
- All students should be able to recognise that the exterior angles of a polygon sum to 360°.
- Most students should be able to calculate exterior angles of regular and irregular polygons.
- Some students should be able to calculate the number of sides in a regular polygon from a given exterior angle.



