The Human Eye 6th Grade Science

Warm-up Be ready for class-have a pencil and take an eyeball guided notes handout from the front table. Think about the pathway of sound for hearing that you learned. Predict where the pathway of sight will go.

Warm-up Take out your notes from yesterday List at least one thing you learned about the eye yesterday. What did you notice yesterday about your partner’s pupils when the lights were turned on after being off? Why did this happen?

Parts of the Eye Lens Eyelid Sclera Eyelashes Orbital Muscles Iris Cornea Optic Nerve Pupil Eye Socket

Cornea Clear covering over the eye

Iris Circular band that controls how much light enters the eye Gives eyes their color Examine your partner’s eyes with the lights off and then with the lights on. What do you notice?

Lens Tissue that bends (refracts) light passing through and helps focus an image

Pupil Hole in the center of the eye which allows light to pass through Why do optometrist dilate your eyes?

Sclera White part of the eye Protects the eye

Retina Layer of tissue on the back of the eye that has cone and rod cells which gather information Rods: allow us to see black, white, & shades of gray Cones: allow us to see red, blue, and green colors They work together so we can see many shades of colors

Optic Nerve Nerve that connects the eye to the brain

Eyelid & Eyelashes Covers & protects the eye

Orbital Muscles Allow eyes to move Humans are the only animal who can “roll” their eyes

How do we see? 1. Light enters the eye through the cornea. 2. Light continues through the pupil which is controlled by the iris. 3. Light passes through the lens which refracts (bends) the light causing the picture to be upside down. 4. The upside down picture travels to the retina where the image is converted to electrical signals. 5. The optic nerve sends signals to the brain, which interprets the images and flips them right side up.

Corrective lenses can improve vision. Nearsightedness Farsightedness A person who is nearsighted cannot see objects clearly unless they are near. Concave lenses can correct the problem of nearsightedness. (Refer to page 129 C) Objects are clearer to a farsighted person when objects are farther away. Convex lenses can correct the problem of farsightedness. (Refer to page 129C)

Surgery and Contact Lenses It is possible to change the shape of the cornea to make the eye refract properly. This can be done by advance surgery and contact lenses.

Quick Videos to Show https://www.youtube.com/watch?v=REVpwKKd8VA https://wcpss.discoveryeducation.com/learn/player/43b27238-3adc-4a23-b113-ad2aea9aca70

Eye Fun Facts Most people blink every 2-10 seconds.Each time you blink, you shut your eyes for 0.3 seconds, which means your eyes are closed at least 30 minutes a day just from blinking. Owls can see a mouse moving over 150 feet away with light no brighter than a candle. The reason cat's and dog's (and cow’s) eyes glow at night is because of silver mirrors in the back of their eyes called the tapetum. This makes it easier for them to see at night. An ostrich has eyes that are two inches across. Each eye weighs more than their brain. A chameleon's eyes can look in opposite directions at the same time. A newborn baby sees the world upside down because it takes some time for the baby's brain to learn to turn the picture right-side up. One in every twelve males is color blind