The Anatomy of a Circle Art and Geometry Lesson

Posted by: 

From what I understand, art classes are becoming squished out of the school's educational agenda.  This really bums me out.  I love art, and believe in the exceptional benefits that come from incorporating math in our children's educational experience.  

This activity will successfully sneak watercolor practice and color mixing right in there with your student's geometry practice.  (The crowd roars,and the superstar math teacher takes a bow!)

What will the Students Learn?

  1. Students will be able to construct a circle using a compass, with a given radius.
  2. Students will be able to label a circle and all its parts, including: quadrant sector, semi-circle, tangent, chord, arc, radius and diameter. 
  3. Students will be able to identify the formula used to find the area of a circle using the radius and diameter.
  4. Students will be able to solve for the area, showing their work.
  5. Students will be able to complete their poster using watercolors, mixing colors as needed, and using techniques as prescribed by the teacher.

How Can You Use This Assignment?

  1. This is a great "Get to Know This Math Concept" Presentation activity
  2. A perfect introduction to a Geometry lesson 
  3. The focus of a classroom or hallway bulletin board
  4. A work sample for parent-teacher conferences.  
  5. The cover for a geometry notebook.
  6. A first of many other Geometry posters, including squares, angles, tessellation's, etc.
  7. An addition to your student's math notebook (I promise, it will be a favorite of theirs.  Students take such pride in work they can put their unique twist into). 

First, go over the definitions with your students, either during a prior math session, or presently as you construct the circle.  I simply showed my students my example, and then gave a brief definition of each, while explaining the entire assignment.  It can be as detailed or brief as you like.  

These are the components I wanted featured on their papers:

  • quadrant sector
  • semi-circle
  • tangent
  • chord
  • arc
  • radius
  • diameter
  • formula for area
  • space to show work using their given radius
  • a title

These are the tools each student should have:

  • watercolor paper
  • pencil
  • compass
  • ruler
  • scratch paper (to work out their problem before putting on final paper)
  • thin, permanent black marker
  • white crayon
  • paints/brushes


First, give each child a radius to work with.  You can assign numbers, or you can have students draw from a hat.  You can have your students roll the dice and add the numbers together.  Whichever way you choose, this spin is fun for the kids, and gives each paper a slightly different flair.  

In front of the class, measure and draw your own radius on the board.  Show how to double the number to get the diameter.  Place the sharp point of your compass on center of the circle, and the pencil on the outside of the radius line.   Create your circle with the compass.  

One by one, label your circle with the above terms.  Ensure understanding by asking questions and monitoring student's comments.  Hint:  Instruct students to not clutter any part of their circle with too many terms.  Give each term adequate space.  

Once the terms are placed on the circle, have students write out the formula for a circle and then write out their math problem in a space nearby.  Add a title.  When finished, and you have checked each students' work (it may be handy to have a cheat sheet ready with all the different answers the students could have), have each student go over all the words (title, formula, math problem, vocabulary terms) with a thin permanent marker.   Then, erase pencil marks underneath the marker.  I instructed my students to leave their circle without an outline, and instead thickly trace it, and all the other portions inside the circle, with a white crayon.  This will set the text apart, and make it easier to read.  

Once the marker and crayon have been carefully applied, students can use watercolor to finish the diagram, mixing colors as needed.  It may be helpful to do the drawing and painting on different days.  Do not rush the painting portion.  It should be a relaxing, non-stress experience, one that will allow them to adequately reflect on the different parts of the circle.  

When finished, allow to dry, and hang up for all to see!  

Are you looking for a great site that will give you all the info you need about the cirlce?  Check with Math Is Fun!   For another Geometric Math Art Lesson, try Drawing and Measuring Triangles Math Art.