Light and the Eye

Lesson 5 Vocabulary

sclera

• Context clue: When I was tired the sclera of my eyes were turning red.

• Definition: The white outer layer of the eyeball.

retina

• Context clue: Don’t look directly at the sun or it may harm your retina.

• Definition: A layer at the back of the eyeball. This is where the visual image is formed.

Optic nerve:

• Context clue: The optic nerve is attached to the brain.

• Definition: a bundle of nerves that send impulses to the brain from the eye

cornea

• Context clue: Don’t rub your eyes or you may scratch your cornea.

• Definition: transparent layer forming the fron of the eye.

iris

• Context clue: Your iris is a beautiful shade of green.

• Definition: The round, colored part of the eye.

pupil

• Context clue: That cat has almond shaped pupils.

• Definition: The hole in the center of the iris where light passes through. The size of the pupil changes in response to light.

vision

• Context clue: The doctor told me that my vision wasn’t good, so I needed to wear glasses.

• Definition: The sense that lets people know what an object looks like.

Steps

• Distribute mirrors• Dim lights – Focus on the shape and size of your pupil

• Turn the lights on and CLOSELY watch how your pupil changes – What happens?

• Do this again, but darken the room completely and then turn the lights on

Processing

• Make a before and after sketch on page 10 in your light notebook

• Discuss question #2 with your partner & then answer independently

• Share answers as a class

Processing Questions

• Do you think light bounces back to your eye when it hits objects?

• How can you tell that light bounces back to your eye when it hits objects?– The pupil reacts to the light so you are able to see

the object • Does the amount of light shining on an object

affect how easily you are able to see it?

Processing Questions

• Does the amount of light shining on an object affect how easily you are able to see it?– If very little light shines on an object, less light

bounces off of it and back to the eye so the object might not be seen clearly

– If more light shines on an object, more light bounces off of it and back to the eye making the object appear clearer and easier to see