A set of Venn diagram worksheets and a PowerPoint designed to put the 'students into a pit' and to work their own way out while making rapid progress within the lesson.
PowerPoint and worksheet on angles in triangles and properties of triangles
You can find the updated version here:
https://www.tes.com/teaching-resource/ks2-ks3-ks4-maths-angles-in-triangles-11815600