## Geometry

### Perimeter and Area

Perimeter and area are basic measurement concepts. In this unit students explore area formulas for parallelograms, triangles, and trapezoids, and then use some of these shapes to visualize and find the area of irregular polygons. They determine the effect on perimeter and area when one dimension of a rectangle is changed, explore arc length and sector area, and find the relationship between the diameter and circumference of a circle.

### Geometry: Perimeter and Area Activities

Title Type

#### The Mailbox

In this lesson, students will visualize that areas of irregular shapes can be found by determining the sum of smaller, more familiar shapes.

• 41

#### Side Length, Perimeter, and Area of a Rectangle

Explore the effects of changing base (or height) of a rectangle on it's perimeter and area.

• 6817

#### Area Formulas

Explore the relationships among the area formulas for parallelogram and rectangles.

• 7646

#### Arc Length and Sectors

Investigate the mathematics of arc length and sectors.

• 6970

#### Exploring Areas of Irregular Polygons

Explore different ways to find areas of irregular polygons using the three basic shapes of rectangles, parallelograms, and triangles.

• 6741

#### Fixed Perimeter Rectangles

Investigate side length and area in a rectangle with fixed perimeter.

• 6345

#### Comparing Perimeter to Area of a Square

Analyze the relationship between the area and perimeter of a square.

• 6387

#### Exploring Diameter and Circumference

Explore the relationship between the diameter and circumference of a circle.

• 6516