Students will learn about perimeter and the units used to measure perimeter using a variety of
materials including their hands, feet, rulers, and computer applets.

Objectives

Upon completion of this lesson, students will:

have practiced finding perimeter of rectangular shapes and irregular shapes with right angles.

understand which units of measure are appropriate for measuring perimeter.

Standards Addressed:

Grade 3

Geometry

The student solves problems using perimeter or area.

Grade 4

Geometry

The student solves problems using perimeter or area.

Grade 5

Geometry

The student solves problems (including real-world situations) using perimeter or area.

Third Grade

Geometry

Reason with shapes and their attributes.

Measurement and Data

Geometric measurement: recognize perimeter as an attribute of plane figures and distinguish between linear and area measures.

3rd Grade

Measurement

The student will demonstrate through the mathematical processes an understanding of length, time, weight, and liquid volume measurements; the relationships between systems of measure; accurate, efficient, and generalizable methods of determining the perimeters of polygons; and the values and combinations of coins required to make change.

The student will demonstrate through the mathematical processes an understanding of length, time, weight, and liquid volume measurements; the relationships between systems of measure; accurate, efficient, and generalizable methods of determining the perim

4th grade

Measurement

Standard 4-5: The student will demonstrate through the mathematical processes an understanding of elapsed time; conversions within the U.S. Customary System; and accurate, efficient, and generalizable methods of determining area.

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

access to a browser

construction paper and pencil

rulers and graph paper

Lesson Outline

Focus and Review

Begin the lesson by asking the students if anyone has a fenced yard and ask them to think about
how you might figure out how much fencing was required.

Objectives

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

Today we are going to be learning about the concept of perimeter and how to calculate perimeter.

We are going to use the computers to learn about perimeter, but please do not turn your
computers on or go to this page until I ask you to.

Teacher Input

Have the class measure the perimeter of their desk top using their hands as the unit of
measure.

Discuss the different answers the students calculated.

Discuss why the answers differed.

Introduce the term perimeter.

Guided Practice

Have the students work in pairs and measure the perimeter of 4 or 5 different objects around
the room using different units: hands, feet, pencils, in, ft, etc.

Monitor the students' progress.

Have a couple of students share their examples.

Discuss why it might be necessary to have a standard unit like: inches, feet, or meters.

Discuss why someone might need to know the perimeter of something. (Example: fencing a yard)

Demonstrate how to use the
Perimeter Explorer. (You may want to specify certain area settings.) Have the students answer a couple of
computer generated problems with you.

Demonstrate how to draw the figure generated by the computer on a piece of graph paper.

Independent Practice

Have the students work either alone or in groups of two with the
Perimeter Explorer.

So you can check their progress, have the students copy the computer generated figures on a
piece of graph paper.

Closure

Draw a grid on the board and draw a few shapes in the grid.

Call on several different students to help you determine the perimeter of each shape.

Review the meaning of the word perimeter.

Review the different units used to measure perimeter.