I really encourage my students to think and figure out patterns with math. So when I needed to teach the idea that all interior angles of a triangle add up to 180, I decided to make it a hands-on activity, as well as looking at quadrilaterals, pentagons, and even hexagons, to see what patterns are formed. Here is an example of one of my students’ work.
Here is a link if you want the complete instructions, worksheets, and answer key.