Circle theorems lesson 1

A complete lesson on the theorem that the angle at the centre is twice the angle at the circumference.
For me, this is definitely the first theorem to teach as it can be derived using ideas pupils have already covered. and then used to derive some of the other theorems.
Please see my other resources for lessons on the other theorems.

Activities included:

Starter:
A few basic questions to check pupils can find missing angles in triangles.

Main:

• A short discovery activity where pupils split the classic diagram for this theorem into isosceles triangles (see cover image).
  If you think this could overload pupils, it could be skipped, although I think if they can’t cope with this activity, they’re not ready for circle theorems!
• A link to the mathspad free tool for this topic. I hope mathspad don’t mind me putting this link - I will remove it if they do.
• A large set of mini-whiteboard questions for pupils to try. These have been designed with a variation element as well as non-examples, to really make sure pupils think about the features of the diagrams.
• A worksheet for pupils to consolidate independently, with two possible extension tasks: (1) pupils creating their own examples and non-examples, (2) pupils attempting a proof of the theorem.

Plenary:
A final set of six diagrams, where pupils have to decide if the theorem applies.

Printable worksheets and answers included.

Please review if you buy as any feedback is appreciated!