Creating and Understanding Circles and Their Parts

This lesson will offer a hands-on opportunity to explore and construct circles. Students will develop a definition for identifying the parts of a circle such as the center, radius, diameter, chord, and circumference. Students will use compasses and rulers in constructing these parts of a circle.

A lesson plan for grade 6 Mathematics

By Patricia Tingen

Learn more

Related pages

• In math, "elegant" means "cool"!: An elegant solution to a math problem is one that requires less time and work. Encouraging students to find such solutions will help them build number sense or numeracy.
• Math Fun: We have compiled some of our favorite mathematics instructional resources to help students develop a sense of numbers and how they are used by us everyday. Students will have fun practicing their skills and trying new problem-solving ideas.
• Beginning lesson on Coordinate Grids-First Quadrant: Students will investigate the first quadrant of the Cartesian coordinate system. They will use online activities developed by Shodor.org to identify the coordinates of points, or plot specific points. Then students will progress to an activity where they direct a robot through a mine field laid out on the coordinate plane. Permission has been granted for the use of the materials as part of the workshop - "Interactivate Your Bored Math Students" by Shodor Education Foundation, Inc.

Related topics

• Learn more about mathematics.

Help

Please read our disclaimer for lesson plans.

Legal

Learning outcomes

Students will:

• construct circles using a compass.
• draw in the following parts of a circle: center, radius, diameter, and chord.
• develop word meanings from the circle part illustrations.

Teacher planning

Time required for lesson

2 hours

Materials/resources

Teacher: overhead projector,compass, and ruler(cm.and in.)

Students: pencil, paper, compass, and ruler(cm. and in.)

Technology resources

No computer is needed for the basic activities of this lesson. You may use a draw software program to create circles and designs.

Pre-activities

Review with students objects with a circular shapes and find these shapes in the classroom.
Review with students the proper way to construct a circle with a compass.

Activities

Session 1: (1 hour period)
The teacher will follow these steps on the overhead projector demonstrating for the students how to construct circles. Using compasses have students construct different sized circles through experimentation. Next have all students construct a circle putting in the center point. Using a ruler students will draw a line segment through the center of the circle with endpoints on the circle. Identify this segment as the diameter of the circle. Label it. Measure the length of the diameter and record length in inches. Next draw a line segment from the center of the circle to a point on the circle. Label this distance as the radius. Measure its length in inches.Compare the lengths of the radius and diameter and draw conclusions about their relationship (Ex.2 radii=1 diameter). Last of all draw a line segment not including the center of the circle but having endpoints on the circle. Label the segment chord. Have students repeat the above steps for drawing and labeling circles but specify the
length of the radius.

Working in pairs, have students check their partner’s circle for accuracy. Students should write the meanings of their circle parts in their own words.

Session 2: (1 hour)

1. Orally review the meanings of circle parts (center, radius, diameter, and chord).
2. Using the overhead projector have student volunteers to label a sample circle for review.
3. Cut off overhead.
4. Ask students using a compass to construct a circle with a 5 cm. radius independently. They will also need to label the center. Using a cm. ruler they will construct the diameter, radius, and chord of the circle.
5. Randomly check student drawings.
6. Use any worksheets or textbook pages that meet the lesson’s objectives for more practice.

Assessment

• Require students to draw a specific size circle and label the circle parts.
• Use sample questions from EOG Testlets to check student understandings.
• Use any worksheets or textbook pages that meet the lesson’s objectives.

Supplemental information

None

Related websites

N/A

Comments

Another extension of this lesson could be allowing students to create circle designs and then color them for various geometrical effects.