1. Entering The Eye
Here We Go. . .

2. You see objects when a process occurs that involves both your eyes and your brain.
Light enters the eye through the cornea. The cornea protects the eye.
After passing through the cornea, light enters the pupil, the part of the eye that looks black.
The iris is a ring of muscle that contracts and expands to change the size of the pupil.

3. More on Iris What does Iris mean in Greek? Hint:
-deals with colors of visible light
-Iris is a Greek Goddess

4. The Human Eye --------------Retina Cornea--------------
Optic nerve
Cornea
Iris
Pupil
Lens

5. After entering the pupil, the light passes through the lens.
The lens is a convex lens that refracts light to form an image on the lining of your eyeball.
When the cornea and the lens refract light, an upside-down image is formed on the retina. The retina is a layer of cells that lines the inside of the eyeball. The retina is made up of rods and cones.
Rods are cells that contain a pigment that responds to small amounts of light. Cones are cells that respond to color.

6. Where does an image form in the eye?
Cones and rods help change images on the retina into signals that then travel to the brain.
The rods and cones send signals to the brain along a short, thick nerve called the optic nerve.
Your brain interprets the signals as an upright image. It also combines the images from each of your eyes into a single three-dimensional image.
Where does an image form in the eye?

7. Correcting Vision
Glasses and contacts are used to correct some vision problems.
Concave lenses are used to correct nearsightedness. Convex lenses are used to correct farsightedness.
A nearsighted person can see nearby things clearly, but objects at a distance are blurred.
A farsighted person can see distant objects clearly, but nearby objects appear blurry.

8. Our Eye Helps Us Memorize Things.
One way to memorize is to make a picture in our minds of what we are trying to remember.
You have one minute to memorize these objects.

9. We Have Only 1 Nose and 1 Mouth. Why Do You Think We Have 2 Eyes?
The brain takes the picture seen by each eye and combines them to make one picture.
Sometimes our brain is tricked
into seeing things that aren’t real.
These are called optical illusions.
Let’s try some!

10. What Does This Say?

11. We Are Now Leaving Ms. Frizzle’s Eye. Now Where Are We Going?!