3990 Learning at home workbook 6 ebook

The Human Body ~ Activity 2
The Structure of the Eye
The Structure of the Eye
Label the eye diagrams by reading the description.
Retina The back part of the eye which
receives the image.
Lens The part of the eye which directs light
onto the retina. It changes shape to
help you focus on objects.
Pupil The small hole in the centre of the iris
which allows light to enter. Its size
alters with the amount of light.
How the Eye Works
The human eye has a design similar
to a camera. The pupil works like a
shutter, growing larger or smaller to
control the amount of light entering.
The lens behind the iris changes shape
to focus the image on the retina at the
back of the eye, just as the lens moves
in a camera to focus the image on the
film at the back.
Iris This is the coloured part of the eye
which you can see. Everyone in the
world has unique irises.
Tear duct The part of the eye which drains away
tears produced by the tear glands.
Eyelids Movable flaps of skin which can cover
or uncover the eyeball.
Cornea The clear covering of the eye over the
iris and pupil.
Optic nerve The nerve which runs from the retina
and carries the image to the brain.
Eyelashes Short thick hairs on the eyelids to
protect the eye from dust.
Inverted Image
Because the light rays cross over each other as they pass through the lens, the image received
by the retina is upside down. The brain inverts the image to what we ‘see’ in real life.
The following activity will illustrate this inversion of the image on our retina.
Question: What does the image received by the retina look like?
Design brief: You will be demonstrating how an inverted image reaches the retina.
Materials: piece of white translucent paper (greaseproof is ideal) about 30 cm 2 ; clean, empty, silver tin with the lid removed but the
bottom in place; an elastic band; a jumper or large cloth to make a dark area over your head.
Steps: 1. Punch a nail hole in the centre of the bottom of the tin (about 1 to 2 mm diameter).
2. Spread the paper over the open end of the tin and secure with an elastic band. Pull the paper taut. This is the screen.
3. Point the bottom of the tin at an outside window.
4. Use the jumper or cloth to cover your head and make a dark area with just the paper screen showing.
5. Study the image as it appears on the screen.
Findings: Draw and label a diagram to show how an image enters the tin’s nail hole and another showing the
image on the paper screen.
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R.I.C. Publications® www.ricpublications.com.au 27 ISBN 978-1-922313-88-1 Learning at home workbook 6