# Geometry in Tessellations

Shodor > Interactivate > Lessons > Geometry in Tessellations

### Abstract

This lesson allows students to examine tessellations and their geometric properties. The activity and discussion may be used to develop students' understanding of lines, planes, angles, and polygons.

### Objectives

Upon completion of this lesson, students will:

• have been introduced to tessellations
• have learned about lines, planes, angles and polygons
• have experimented with the area and perimeter of polygons

### Student Prerequisites

• Arithmetic: Student must be able to:
• identify polygons
• measure angles
• understand congruent figures
• 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

• pencil and paper
• Copies of supplemental materials for the activities:

### Key Terms

 polygon A closed plane figure formed by three or more line segments that do not cross over each other regular polygon A polygon whose side lengths are all the same and whose interior angle measures are all the same tessellation A tessellation is a repeated geometric design that covers a plane without gaps or overlaps

### Lesson Outline

1. Focus and Review

Remind students what has been learned in previous lessons that will be pertinent to this lesson and/or have them begin to think about the words and ideas of this lesson:

• Ask students if they remember what polygons are, and what makes regular polygons unique.

2. Objectives

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

• Today, class, we will be talking more about the geometry involved in tessellations, and we will discover which types of polygons tessellate a plane.

3. Teacher Input

Explain to the students how to do the assignment. You should model or demonstrate it for the students, especially if they are not familiar with how to use our computer applets.

• Open your browser to the Tessellate! page in order to demonstrate this activity to the students.
• Show students how to select one of the regular polygon shapes and click the "tessellate" button to see it displayed.
• Ask students to count the number of sides of the polygon.
• Record the number of sides in the data table , and help students complete the rest of the information for the shape you have chosen.

4. Guided Practice

Try another shape, letting the students take the lead in completing the data table for this new shape.

• Encourage students to determine a pattern among the regular polygons that they work with. Ask the students to predict which regular polygons will and will not tessellate and why.
• Select the third regular polygon, observe what it looks like in the Tessellate activity, and then complete the data table for this shape.
• Ask students what the data table would look like for 5, 7 and 8-sided polygons.
• Help students analyze the data and draw a conclusion about which shapes will tessellate the plane and why.

5. Independent Practice

• Print out copies of the Tessellations on Paper Worksheet and distribute them to students.
• Alternatively, have the students complete a similar exercise on the computer using the Tessellate activity, a screen capture utility and a drawing program.

6. Closure

You may wish to bring the class back together for a discussion of the findings. Once the students have been allowed to share what they found, summarize the results of the lesson.

### Alternate Outline

This lesson can be rearranged in several ways if there is only one available computer:

• You can model all the parts of the lesson for the students, asking them to complete the data table with you as a class.
• Model the connect the dots activity to the whole class on the computer using the Tessellate activity, a screen capture utility and a drawing program, but then distribute the Tessellations on Paper Worksheet to each student to complete individually.

### Suggested Follow-Up  