MethodDraw any four sided shape you like on paper, as irregular as you can make it. Colour each of the four corners a different colour. Tear or cut the four corners off. Now arrange all four torn corners so their points meet at one spot, edge to edge with no gaps and no overlaps.
What happensThey go exactly once round the point, with nothing left over and nothing missing. A full turn is 360°, so the four angles of your quadrilateral add to 360°.
Then ask the harder questionDoes this prove it, or only suggest it? Forty torn shapes all working is convincing, but it is not proof. The proof is the diagonal argument: split it into two triangles, and 180 + 180 = 360.
🔐
That's a peek at activity 1 of 4 - sign in for all of them, full length.