# Area Explorations

Shodor > Interactivate > Lessons > Area Explorations

### Abstract

In this lesson, students will explore the area of irregular shapes to find multiple different methods for calculating area.

### Objectives

Upon completion of this lesson, students will:

• have practiced finding area of irregular shapes with right angles.
• understand that area can be found in multiple ways.

### Student Prerequisites

• Technological: Students must be able to:
• perform basic mouse manipulations such as point, click and drag
• use a browser for experimenting with the activities

### Teacher Preparation

• computer connected to projector
• dry erase markers
• markers or crayons (three different colors for each group)
• record sheets and pencils

### Key Terms

 area The number of square units needed to cover a surface

### Lesson Outline

1. Focus and Review

Using the Shape Explorer applet, draw a rectangular shape for the students to see. Activate prior knowledge using these guiding questions:

• How would you find the area of this shape?
• Are there other ways to find the area?
• How do you know that these methods work?

2. Objectives

Let the students know what they will be doing and learning today. Say something like this:

• Today, we will be learning about finding the area of irregular shapes.
• We will be looking for several methods to solve each problem.

3. Teacher Input

• Project an irregular shape on the board.
• Discuss with students different ways to find the area of the shape.
• Include counting the squares individually as well as breaking the shape into smaller rectangular shapes as methods for finding the area.

4. Guided Practice

• Project an irregular shape on the board using the Shape Explorer applet.
• Have students volunteer to draw outlines of the smaller shapes that compose the bigger shape.
• Look for at least 3 methods for finding the area for each shape.
• For each method, compose a number sentence.

Use the following chart as a guideline:

 Picture Number sentence Area (1x4)+(2x7)+(1x3) 21 square units (3x4)+(2x3)+(1x3) 21 square units (3x1)+(4x3)+(2x3) 21 square units

5. Independent Practice

Break the students into groups of three and give them the following instructions:

• For each shape that is projected on the board, your group is to come up with three different ways of finding its area.
• Using the record sheet, write down number sentences for those three methods.

For each shape, give the students a set amount of time to develop methods. Then have the each group share their methods to see how many methods the whole class used.

6. Closure

Lead the class in a discussion about how they found the area for a given shape. Ask the students how the developed new methods of finding the area each time.

### Suggested Follow-Up

Students who have mastered the skills necessary to find the area of irregular shapes may be ready to learn about finding triangle area or surface area and volume. 