This is a Mathematics lesson based on the New Common CORE Standards. It addresses 7th grade standard 7.GB.5 but I have used it with my 5th grade class. It is meant as a problem solving task for students to introduce them to solving for the unknown angle of a triangle. The lesson presents them with a theory that all angles of ANY triangle when added will equal 180 degrees. They will then work in small groups to either prove this is correct or incorrect.
At the end of this lesson students will understand why adding the sum of two known angles and then subtracting from 180 degrees works and where the formula comes from.
My name is Melanie Whitesides and I have moved to 5th grade this year. I strongly believe in giving students challenging problems to solve in order to prepare them for the real world. Math is a subject that many students begin to give up on if not approached the right way. As with any math task, the more tasks you give your students - the better they become at solving them. Treat it as you would a mystery or a puzzle because that is what it is.
Math Task - Proving Triangles Equal 180 Degrees
by Melanie Whitesides
is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License