## Brain Activity

Summary: When you look at something, your eyes see it upside down and reversed. The brain changes the image so it looks as it should. Each eye sends a slightly different message to the back of the brain, and the brain interprets the message so you understand what you are seeing.

Since each eye sees things a little differently, if you cover one eye what you see will change position. Your group will record what happens when you use only one eye and then both eyes.

1. Plan It

Prepare the equipment. Cut out three yellow circles that are 5 cm, 15 cm, and 25 cm in diameter. Cut out two red circles that are 10 cm and 20 cm in diameter. Glue them together so they make a target.

Make five small clay balls.

Target and clay balls prepared

2. Put It Together

Set up and run your experiment.

• Place the target flat on a table. (You may wish to tape the target down.) Have one person stand about four feet from the target and cover one eye.
• Have another person hold a clay ball over the target. The first person tells the ball-holder to move the ball over the target so that when they drop it, it will land in the middle of the target.
• Record where the ball lands on the target. Use tally marks on a chart as shown on page 431 of the Math Central textbook, or print the Individual Data Chart found here on Education Place. Have each person drop the clay ball five times for each eye and then five times using both eyes.
• Combine your data to complete the Group Data Chart as shown on page 431 of the Math Central textbook, or print the Group Data Chart available here on Education Place. Make sure to put your numerical data in the right position on the chart when recording the ratios.

Our experiment completed and results recorded

3. Wrap It Up

Present the results about your experiment. Make a circle graph that shows what percent of your group hit the 5 cm circle using the left eye, right eye, and both eyes.

Write a paper explaining your results. Predict the probability of getting the same results with a different group of students.

Presentation completed

4. Discuss Your Results

• How accurately did your group combine the results of the experiment?
• Does each group member's chart clearly show the data?
• How clearly does your group chart and circle graph show your final data?
• How did your group divide the work to prepare the tables?
• How is this experiment helpful in understanding how vision works?

Review completed

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