Make a Benham Disk
In 1894, toy maker Mr. C.E. Benham noticed that he saw color when looking at the black and white patterns he had placed on a toy top. He began making the tops and selling them to toy stores around the country. Toy tops with Benham’s design continue to be sold today.
Exactly how the disk works is a mystery. Scientists believe that the retina perceives the varying sizes of lines in different ways because of the way the cones interpret and process the the light received.
Our eyes have three types of cones, each sensitive to either short, medium, or long wavelengths of light. Each wavelength corresponds to a color–red, green, or blue. Each type of cone has a different response time when it is stimulated. Each type of cone also hangs onto its color for different amounts of time. We have included a QR code below to Flinn Scientific, which thoroughly explains what is happening.
IMPORTANT NOTE: Want to teach your children more about rods and cones? Download our human eye printable pack over here.
Make a Benham Disk
Equipment
- 1 Set of printables Request them below
- 1 Pack of wooden skewers
- 1 Piece of cardstock If you do not have cardstock, print on regular paper. Then, reinforce with posterboard or thin cardboard.
Instructions
- Print the following pages on the card stock or print on plain paper and use poster board to reinforce the paper. The poster board should be the same size as the circle.
- Carefully cut out each disk template carefully. The process must be as round as possible.
- Poke a small hole in the disk's center with the half-skewer. You want to use the half with the sharp point.
- Insert the piece of skewer into the hole. You will need to wiggle the skewer a little so the disk will spin freely on the stick.
- Hold the stick and spin the disk. The colors are seen best at slow speeds (between 3-5 rotations/second).
Video
Download the Benham Disk Printable Pack
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- Information about optical illusions
- This blog post and instructions
- Templates
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I hold a master’s degree in child development and early education and am working on a post-baccalaureate in biology. I spent 15 years working for a biotechnology company developing IT systems in DNA testing laboratories across the US. I taught K4 in a private school, homeschooled my children, and have taught on the mission field in southern Asia. For 4 years, I served on our state’s FIRST Lego League tournament Board and served as the Judging Director. I own thehomeschoolscientist and also write a regular science column for Homeschooling Today Magazine. You’ll also find my writings on the CTCMath blog. Through this site, I have authored over 50 math and science resources.