## Lesson: Area Formulas

Introducing the Concept

Since your students have found the area of rectangles before, this is a good concept to build on to help them understand the formulas for finding the area of a triangle and a parallelogram.

**Materials: ** an overhead transparency of a grid, a cutout of a right triangle with one side 6 units long and another side 3 units long, a cutout of a right triangle with one side 6 units long and another side 5 units long, rulers, an activity sheet with four triangles drawn on it with the height and base measures provided for 2 of the triangles.

**Prerequisite Skills and Concepts: **Students should know what area is and how to find the area of a rectangle. They should know that area is measured in square units.

On the overhead transparency, draw a rectangle with a length of 8 units and a width of 6 units.