Eyes are some of the most complex structures of the body.  They use light and electrical impulses to allow our brains to see our surroundings.

Human eyesight is our strongest of the senses.  Our eyes have a lens that focuses light onto the back of the eye, a curved screen of light-sensing nerve cells.  When the image hits the back of the eye it is upside down and our brain turns it back right side up.  We can see color because we have specialized cones (those nerve cells) that allow us to see color.  We also have rods, the black and white vision cells.  Many animals, like dogs, have only rods, no cones and so they cannot see color.

Dominant Eye

Did you know that just as you are right or left handed, you are also right or left eyed?  Try this to find out which is your dominant eye.

  1. Form your fingers into a triangle with your thumbs and pointer fingers overlapping each other. 
  2. Stretch your hands out in front of you and pick a target at least ten feet away. 
  3. Sight the target through the triangle of your fingers. 
  4. Now close one eye and then the other without moving your hands or your head. With one eye you will still see the target perfectly. This is your dominant eye. With the other eye, the target will disappear from the triangle of your fingers.   


You can do an eyeball dissection at home.  Get a kit from Home Science Tools for around $7.  It contains a cow eye, a dissection tray, a dissection tool, and instructions on how to do the dissection.


Here’s a Human Eye Diagram to label.

The answers are:

  1. Optic nerve
  2. Retina
  3. Lens
  4. Cornea
  5. Pupil
  6. Iris
  7. Vitreous Fluid

The optic nerve sends signals to the brain.  The iris is the colored part of your eye.  The retina is where the eye projects images.

Additional Layers

  • Talk about keeping your eyes healthy.  Reading in good light, protecting them by wearing glasses or goggles when doing dangerous stuff, and so on.   
  • Why are some people color blind?  Find out.
  • Why do cat’s eyes glow at night?  What about other animals, like grasshoppers.  How do their eyes work?
  • If you golf or shoot guns or arrows, you need to know your dominant eye.  Why?
  • This lesson can be found in Unit 2-9 of the Layers of Learning most un-curriculumy curriculum.


Layers of Learning Unit 2-9

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