Discovering Area Relationships of Polygons
6th grade
Description
Students discover the area formulas for triangles, parallelograms, and trapezoids. They apply formulas to find areas of irregular shapes.
Hook
This can be done as a whole class or with partners. Project (or provide copies) of the "Cork Costs" graphic. Ask students: What do you notice? What do you wonder?
Lessons
Lesson 1 of 4
Students develop the area of triangles formula using the area of rectangles and by comparing triangles with equal bases and heights.
Lesson 2 of 4
Students use prior knowledge of the area formula for rectangles and triangles to discover the formula for the area of parallelograms.
Lesson 3 of 4
Students explore several strategies for calculating the area of a trapezoid while discovering the area formula for trapezoids.
Lesson 4 of 4
Students will estimate the area of irregular shapes and use a process of decomposition to calculate the areas of irregular polygons.
ARC Assessment
Technology Resources