It's possible to demonstrate and prove mathematically that the angle sum of every triangle is 180 degrees. The techniques used are useful for solving all kinds of other geometry problems too.

(typical responses: size, all triangles, all coloured, all have three sides, all pointed the same way (orientation), all have angles). 2. After the initial discussion about the static triangle images, ...

So many problems can be cracked by reducing them to triangles that there’s an entire mathematical discipline, trigonometry, ...

Big Idea – We can describe, measure, and compare spatial relationships. to build on students' knowledge of triangle and to develop students' reasoning with properties of triangle to develop students' ...