Children will love the excuse to turn out classroom lights while science teachers perform magic tricks based on simple scientific facts. Place a black towel on the floor and create a shield on a bright desk lamp so it will only cast light downward. Choose three students to sit in a circle on the floor and place their hands on one another on the towel. Turn out the classroom lights and wait two minutes so all eyes have time to adjust. Turn the lamp on for no more than one second before extinguishing. Students should slowly raise their hands but keep their eyes fixed on the same spot. After five seconds, a white image of the hands will appear and turn to shades of pink, green and blue before disappearing.
Students will see many colors of black and white, but need adult supervision to operate an electric drill. Gather the drill, typing paper, scissors, glue, a black marker, and an old CD. Trace the CD on paper and cut out around the edge and through the center hole. Make a striped or checkered patten with the marker on the paper disk. Glue the paper disk on the CD and set on the electric screwdriver. Turn the screwdriver on and observe the CD in motion. Rove eyes over the disk and record all the colors seen near the disk's center and farther out. Compare observations to see if most students achieved similar results.
Students will enjoy working with partners to learn about the finite processing abilities of light rods and cones. Cut typing paper sheets in half lengthwise and distribute a strip to each student, along with a black marker. Instruct them to draw a small dot on one end of the paper and an x on the other end. Partners should take turns holding the marked strip in front of the other person, about an arm's length away. The student looking at the strip should focus on the x while keeping the dot in peripheral vision. The partner should move the paper closer to the other student's face until the observer notices that the dot seems to disappear and, shortly after, reappear. This is the blind spot. Partners should measure how far from the person's eye their blind spot is located and determine whether it is consistent for all students.
Students can use flashlights and colored cellophane to determine the effect of different colors on night vision. Darken a room and place a sheet of colored cellophane over each of four flashlight. Illuminate the bulbs one at a time and instruct students to record what they see. Begin mixing colors by turning on two flashlights and slightly overlapping their beams. Students should record observations of what occurs where the beams cross. Add a third light beam, and finally all four colors. Discuss whether the presence of multiple colors aids or inhibits light rods in processing visual information in the dark.