The lesson starts y reviewing how you calculate area of a triangle. The math slideshow lesson takes a triangle, makes a similar triangle, flips it over and puts both triangles next to each other to reveal a parallelogram. THE ANIMATION ON THIS IS FABULOUS! My students really love this! To find area of a parallelogram you multiply base times height. However the animation shows that you only want to find half of the area (or just 1 triangle not 2.) So the lesson shades in one of the triangles and shows that is why you multiply base times height and then divide by 2.
The lesson continues to show students how to discover the formula for area of a trapezoid. It takes a trapezoid, makes a similar trapezoid, flips it over, and puts both trapezoids next to each other (very similar to the triangle demonstration.) THE ANIMATION ON THIS IS AMAZING! When you do this you have 2 trapezoids put together that make a parallelogram. The slideshow walks you through why you add base 1 plus base 2, then multiply by the height, and lastly divide by 2.
The lesson continues with several examples for students to try. The lesson ends with study guide notes for students to take at the end, which review all concepts taught in the lesson.
To see more information on the all of the math slideshows visit