Today we are going to look at the sense of sight !!!
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Why is sight so important?
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Experiment Time!!!
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Lets Predict: 1. What do you think happens if a flash light is
shone straight into your eyes? or 2. What do you think will happen
to your eyes when in a dark room?
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Functions!! Eyebrow = Keeps sweat from the eye! Eyelashes=
Protects the eye by keeping dust out! Eye lid= Protects the eye by
blinking!
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Functions!! Sclera = white part of the eye. It covers the eye
and protects it! Cornea = transparent, it allows light to enter the
eye. It helps the eye focus as light makes its way in. The cornea
helps to bend light into our eyes.
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Functions!! Behind the cornea: Lens=The lens is the transparent
part in front of our eyes. It helps to bend light onto the retina.
Iris = gives the eye its colour. It also controls how much light
enters the eye by changing shape! Pupil= black circle in the centre
of the iris. It lets light enter the eye!
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Functions!! Tear- duct = cleans the eye by producing tears!
Retina = recognises light! Optic nerve = sends messages from the
eye to the brain!
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What happens when too much light enters the eye???
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When light shines into the eye, the pupils get smaller. How
does this happen??
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When light enters the eye, the iris makes the pupil change. The
pupil becomes small to stop too much light entering the eye.
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When there is not a lot of light entering the eye, the pupil
enlarges!
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How do we see??? When light passes through the eyes lens and
the image hits the retina, the image is actually upside down. This
message that the optic nerve brings to the brain is upside down
too. BUT luckily, your brain knows how to flip the image over so
its right- side up!
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Have your eyes ever played tricks on you?!!!
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What word do you see???
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Are the circles moving???
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What colours do you see???
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What word do you see???
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What do you see???
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How many faces do you see???
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The blind spot is the area on the retina without receptors that
respond to light. Therefore an image that falls on this region will
NOT be seen. It is in this region that the optic nerve exits the
eye on its way to the brain. To find your blind spot, look your
piece of paper.
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Blind Spot Close your right eye. Hold the image (or place your
head from the computer monitor) about 20 inches away. With your
left eye, look at the +. Slowly bring the image (or move your head)
closer while looking at the +. At a certain distance, the dot will
disappear from sight...this is when the dot falls on the blind spot
of your retina. Reverse the process. Close your left eye and look
at the dot with your right eye. Move the image slowly closer to you
and the + should disappear.
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Depth Perception Two eyes are better than one, especially when
it comes to depth perception. Depth perception is the ability to
judge objects that are nearer or farther than others. To
demonstrate the difference of using one vs. two eye to judge depth
hold the ends a pencil, one in each hand. Hold them either
vertically or horizontally facing each other at arms-length from
your body. With one eye closed, try to touch the end of the pencils
together. Now try with two eyes: it should be much easier. This is
because each eye looks at the image from a different angle. This
experiment can also be done with your fingers, but pencils make the
effect a bit more dramatic.