MNM: Area of Trapezoids… WHY??

WHY?!?! The most intriguing question that I ask and try to have an answer for.  So I was about to teach how to find area of a trapezoid, and I thought I could just teach them the formula and how to use it, but then the question hit me... Why??  Why is the formula like this???My students had a formula chart we refer to as the "cheat sheet" (they get to use this on their STAAR test)...