Give the students the area formula for a rectangle, length x width, and have students draw a rectangle. Have students draw a triangle and see if they can derive the area formula using the drawing of a rectangle. The students should be able to explain their results. You can do the same with trapezoids. The origins of the tangram puzzle are not known with any certainty, but the idea is thought to have originated in China about 250 years ago.
Students create designs using geometric shapes.