CAN YOU SEE IT? BACKGROUND: Eyes are exceedingly important parts of the human eye, for they aid with vision by connecting movement and light. Just like with any other body part, the human eye is made of smaller parts, including the lens, pupil, retina, and optic nerve. Firstly, the black part in the middle of eye is called the pupil, which helps the light enter the eye. After, the light enters the lens. The lens helps the eye focus on the object so that the brain is able to tell depth. Also, the retina takes the picture being seen and sends electrical signals to the brain. These signals turn the picture right side up and add color. Lastly the optic nerve helps send messages to the brain so that the image can be analyzed and understood. The idea of depth perception is prevalent throughout this lab. Depth perception helps identify an object as 3-dimensional and also gives a person perspective about what objects are close by and what objects are farther away. Binocular disparity is caused because both the left and right eye see slightly different images. It is when these images are sent to the brain that the images are put together and the person is able to comprehend the distance. OBJECTIVE: Students will conduct this experiment to realize one of the many important functions of the eye; depth perception. HYPOTHESIS: Closing one eye while performing the experiments will be harder than keeping both eyes open because depth perception will be affected. DURATION: 30 minutes SET-UP TIME: 5 minutes EXPERIMENT’S RUN TIME: 30 minutes TAKE-DOWN TIME: 5 minutes MATERIALS: • •
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Disposable paper cups Quarters Colored chocolate candies (M&M candy) Pencils
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1. Divide the class in half. 2. Have half of the class perform Experiment A and the other half perform Experiment B. 3. In each half of the class allow the students to make groups of two. 4. Make sure the students fill out their data charts. 5. After the students have completed their experiments, come together to discuss and compare results. Experiment A: Penny Catcher 1. 2. 3. 4.
Have your partner sit in a chair. Place a cup on the table in front of them. Have your partner close one eye. Stand behind your partner and hold the quarter about eighteen inches above the table. 5. Move the quarter slowly and tell your partner to say “Drop it!” when they think it is above the cup. 6. Record on your data table whether or not it was caught in the cup. 7. Repeat this experiment two more times with one eye closed. 8. Once three trials are completed, repeat steps 4-6 with both eyes open. 9. Perform three trials with both eyes open and record the data in the table. 10. Next, switch places with your partner and do the same experiment (steps 1-9) except instead of a quarter, use one of the colored chocolate candies. Experiment B: Touch the Pencils! 1. Have your partner sit in a chair. 2. Give your partner an unsharpened pencil. 3. Hold another pencil horizontally in front of your partner. 4. With one eye open, ask your partner to try to make the erasers of both pencils touch. 5. Repeat this experiment 4 more times. 6. Once 5 trials are completed, repeat steps 3 and 4 with both eyes open. 7. Perform 5 trials with both eyes open and record the number of successful trials in the table. 8. Now, switch places with your partner and perform the same experiment. FIGURES, TABLES, PHOTOS: Experiment A Directions: Fill out the chart. Write down whether you caught the item (quarters or chocolate candy) in the cup. Example: Yes or No. Chocolate Candy
Quarters Page 2 of 4
Closed Eye
Trial 1: Trial 2: Trial 3:
Trial 1: Trial 2: Trial 3:
Both Eyes Open Trial 1: Trial 2: Trial 3:
Trial 1: Trial 2: Trial 3:
Experiment B Directions: Fill out the chart. Write down if you could touch the pencil eraser end with one other. Example: Yes or No Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Closed Eye Both Eyes Open
DATA ANALYSIS: 1. Was it easier to catch the penny with one eye closed or with both eyes open? Why do you think that is? 2. What happened when you tried to make the pencil touch when you had one eye closed? 3. Why do you think it was easier to make the pencils touch or catch the penny with both eyes open? 4. How do you think eyes and the idea of depth perception help you in the real world? 5. Why is it important that we use both eyes to see things and not just one eye? CONCLUSION: This lab introduces the idea of depth perception and how important it is for both eyes to be used when seeing. In Experiment A children will notice that the larger the object the more accurately they will be able to catch it. This is because a larger object has more surface area and is therefore easier to catch. Larger objects are also easier to perceive. In Experiment B the importance of using both eyes is also emphasized. Children will notice that when closing one eye it is easier to touch the pencils than when they use both eyes. This helps them understand that by using both eyes they are able to sense depth perception. TEACHER NOTES: 1. Lab can be introduced by asking kids what they see around them. After they mention their observations, explain that their eyes are the major organs that help Page 3 of 4
them see. Emphasize that without eyes they would not know the color of their hair, what their friends look like, or where they are going. 2. Experiment A can be extended by dividing the M&Ms into specific colors. Students can see if they are able to catch a specific color more than others. 3. Experiment B can be extended by having students time how long it takes them to touch the pencils. 4. Make two different stations so that each station is experiment specific. This will help reduce confusion.
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