# 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 Assessement

### Technology Resources