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Image Decoder

This relay-race/puzzle game will reinforce the similar, yet unique, functions of the rods and cones in our eyes.

Images are formed by the combination of information received by rods and cones on the retina. Rods are better at discriminating between different brightness levels (light vs dark), while cones are better at perceiving different colours.

The game can be played indoors or outdoors as outlined in the extension activity.


  • Describe the purpose of rod and cone cells.


  • Per Class or Group:
    small container (box, bucket, bin)
    image templates

Key Questions

  • Did rods and cones see the same image?
  • What was different about the image?

What To Do


  1. Print out templates (one colour, one black and white). You can also enlarge the image and print it onto 11″x 17″ sized paper to improve visibility.
  2. Cut each image into 15 puzzle pieces. Laminate the pieces if desired.


  1. Gather students at one end of an open indoor space (classroom or gym would work.)
  2. Put the puzzle pieces into the container and place the container at the other end of the play area.
  3. Gather the class in a circle. Assign students to a team (rod or cones) by alternating their placement.
  4. Starting in one place on the circle, one member of each team will run to the container and pick up an image piece. If they’re on Team Rods, they should pick up a black & white puzzle piece; if they’re on Team Cones, they should pick up a colour puzzle piece. Students then run back to their place in the circle.
  5. Once a team has collected a few puzzle pieces, they can begin assembling their image. The completed image will contain all 15 pieces.
  6. The first team to assemble their image correctly wins.


  1. In an outdoor space, gather students into 2 Teams: Team Rods and Team Cones. Both teams will compete to collect the puzzle pieces in the fastest amount of time and the first team to assemble their image correctly wins! As before, Team Rods will work on collecting the black and white puzzle pieces, while Team Cones will work on collecting the coloured puzzled pieces.
  2. Assign one or two students to monitor and help each team as they work to complete their respective puzzles.
  3. Have each team form a separate line parallel to each other. One member of each team will run and ”perform a task” while making his/her way to the opposite end of the field/ play area to collect a puzzle piece for their team.
  • Note: “Perform a task” means that each students has to complete a fun action such as running backwards, hopping like a rabbit, skipping, dancing, etc.
  1. Repeat this step with the other team members until all pieces are collected and one of the two teams completes their puzzle.