Welcome to the world of missing parrots. I couldn't resist that really bad pun. In fact, this video is filled with them!!! If you're asking what I mean about missing parrots then ... Polly Gone. Get it? No ... don't worry! You're probably here for the Maths. Well, the good news is that I spend time looking at what a polygon is and how we can find the angle sum of any polygon. I do this by using one simple rule: Angles in a triangle add to 180 degrees. I look at a general rule and then spend time using some examples to show how to find the number of sides if I know the angle sum and how to find the angle sum if I know the number of sides. I look at convex and non-convex shapes and then onto the very exciting idea of interior and exterior angles. I don't think there could be any more fun had in one lesson. We also speak a little greek!