KEY IDEAS

• Eyes detect light, color and differences in brightness
• Light travels into, and through, the eye
• The brain makes sense of what the eyes see

EXAMPLE QUESTIONS

• What do your eyes do?
• How do some animals’ eyes differ from human eyes?
• How do you tell the difference between bright and dim light?

EYES DETECT LIGHT

• Eyes can detect different brightness and colors.
• Light travels to the eyes and enters them through the pupils.
• The iris controls the size of each pupil to let in more or less light.
• The lens of an eye focuses the light onto the retina at the back of the eye.
• Images of what the eyes are focusing on form on the retina, which contains sensitive receptor cells that convert the light into signals.
• The signals travel, via the optic nerves, to the brain which interprets these signals.

ANIMALS’ EYES

• Animals’ eyes differ from human eyes.
• Cats and dogs have much better night vision than humans and their eyes are more sensitive to movement.
• This means that they are good hunters.
• Other animals, like horses, have eyes pointing sideways rather than straight ahead.
• This gives them very good peripheral vision.
• This helps them to detect predators.
• Hunting birds, such as eagles and owls, have excellent binocular vision which help them to spot their prey from a long way off.