1.)Pass out geoboards, rubber bands, construction paper sheets, and scissors.
2.) Allow students time to experiment with boards.
Have students cut construction paper into a square that fit the individual squares of the geoboard.
Explain to students that their construction paper square is their unit of measurement.
Have students create a closed figure with their rubber bands on their geoboards. (Any figure will work)
3.)Allow students time to find the area of their polygon by using their unit of measurement.(construction paper square)
**Some students will realize that they will have to half or quarter their figure in order to measure their entire polygon.
After this initial measurement you will want to discuss with your class that in order to find the area you must cover the entire 'inside' with the unit of measurement. This may lead into a discussion of halves and quarters of their construction paper square. You may also want to allow students to tally every time they move their measuring unit in order to keep up with how many units they have used.
4.)Repeat previous steps as many times as needed until students begin to 'see' the area of their polygons.
5.)After students become comfortable with measuring with their construction paper unit, then you need to lead them into visualizing width and length. This should lead into a discussion of area equals length X width. This would be a good time to write the equation for area and lead into questions about what type of polygons this equation will solve. (rectangles and squares).
6.)Now lead students to make triangles and measure with their construction paper units. Lead them to visualize the formula for finding the area of a triangle. A=1/2BXH. Hopefully, students will begin to 'see' this as they have to half their construction paper measuring unit.
7.)Finally, after working several rectangles, squares, and triangles students will understand the concept of A=LXW and A=1/2BXH. You can lead students into further work with these formulas on paper without the manipulatives.