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Exploratorium Field Trip Pathways

Eyeballs

State Standards Addressed:

Grades 9 - 12

 

Biology/Life Science
Physiology
9, a, d,e
Investigation and Experimentation

Grade 7
Focus on Life Science

Structure and Function in Living Systems
5. a, b, g
Physical Principles in Living Systems (Physical Science)

6, a, b, c, d, e, f

Investigation and Experimentation

In this pathway, we will take a look at our own eyes and how they work. There are many ways to learn about the eye and its place in our visual system, including looking at the inside of a cow’s eye, looking into our own living eye, and experimenting with our vision.

Can't find an exhibit or have a question? Ask an explainer

 

Cow's Eye Dissection
*Cow eye dissections are conducted throughout the day at the demonstration table
Cow eye dissection on-line

Listen and Do:

  1. What are two differences between a cow’s eye and a human eye?
    The cow's eye is bigger, it's iris is only one color, it has a tapetum, it's corneas are tougher.
  2. What does it mean "to focus?"
    To adjust your eye or a lens in order to see something clearly.
  3. What parts of the eye do this?
    The cornea, the lens, and the muscles that attach to the lens.
  4. What happens to one of those parts when we shift our focus from far away to near?
    The lens goes from being flatter to more bulging in the middle
  5. What does the part of the cow’s eye called the "tapetum" allow the cow to do?
    See better when there is very little light.

  6. When might we notice this feature in a live animal?
    On a road side at night, when our headlights are in it's eyes.
  7. In what animals have you noticed it?
    Dogs, cats, raccoons, deer, skunks, opossums, squirrels, coyotes, mountain lions, etc..  
  8. What does the iris surround?
    The pupil.
  9. What determines the size of that "hole" in your eye?
    How much light there is shining on it.
  10. What determines the color of your iris?

    The amount of melanin.

    More Experiments:

    (note: if you decide to touch the cow’s eye, you must wash your hands with hot water and soap afterwards)

  11. Describe what the lens feels like.
    Somewhat squishy, but with a more solid center.
  12. What color does melanin stain your fingers?
    Black!

Blood Vessels of the Eye
Cross-Reference Entry

 

Remember seeing the red blood vessels in the back of the cow’s eye? Now look at your own!

 

Read and Do:

 

  1. Why don’t we notice these vessels all the time?
    Our constantly moving eye does not allow us to focus on this relatively small image on our retina, especially when there are many other objects in our field of vision, many of which are moving.
  2. Are these vessels in front of, or behind, our retina?
    In front.
  3. How do you know this?
    If they were behind our retina, they would leave no image upon it.

 

Corpuscles of the Eye
Cross-Reference Entry

 

Look inside your own eyeball!

 

Read and Do:

  1. What do you see when you look at the blue light?
    Little whitish specks moving around in a rhythmic, jerking motion.
  2. Do you notice any rhythm to the movement you see? What is this rhythm?
    It's the same rhythm as your heartbeat!

Macula
Cross-Reference Entry

The macula is a part of your eye that helps you see in a deep blue sky.

 

Read and Do:

  1. What do you notice when the light changes?
    When the light changes from purple to blue, most people see a smudge on the screen.
  2. What is it that you are noticing?
    The shadow of your macula, a yellowish spot on your retina that helps filter out blue light. This feature is important since we are constantly bathed in the blue light of the sky.

Afterimage
Associated Snack
Cross-Reference Entry

Bright light can leave a lasting impression.

Read and Do:

 

  1. What happens after the flash of light, when you look around you?
    You see an image of "+ +" no matter where you look.
  2. About how long does the effect last?
    Depends on the person, but ususally up to about a minute.
  3. When have you noticed this effect before?
    After accidentally looking at the sun or a bright lightbulb for too long.

Pupil
Associated Snack
Cross-Reference Entry

This exhibit allows you to "manually override" what is usually an automatic body response.

Read and Do:

  1. In what light is your pupil the biggest?
    In low light.
  2. In what light is it the smallest?
    In bright light.
  3. How could you repeat this experiment at home?
    You can do it in a mirror at home with a flashlight or near a light switch.