Investigating the Eye

Specific terms introduced in this Unit include:

Cornea
Sclera
Eye lids
Lens
Iris
Optic nerve
Vitreous
Einstein
Retina
Brain
Orbit

Students work in pairs to investigate some effects of light on the pupil, the iris and the blindspot of the retina. They can check their findings with the 3VI CD-ROM

Resources

3VI CD-ROM (optional)

A bright location

A darker location

----------------------------------------------------------

Student Activity Sheet See! Wide Eyed

With your partner, stand in a bright place – in front of a window for example.

(Benny says: ‘Don’t look at the sun!)

Take it in turns.

Look at your partner’s pupil, the dark dot in the middle of their eye.

Notice how large the pupil is, compared with the coloured iris around it.

Now go to somewhere much darker. Look into your partner’s eyes again.

How large is the pupil now?

Has anything changed? (Make notes below)

__________________________________________________________

For even more dramatic results:

Your partner shuts their eyes and covers them with their hands for at least ten seconds.

When you tell them to, they open their eyes.

What happens to their pupils?

__________________________________________________________

What happens to their iris?

__________________________________________________________

Look at their iris. Tiny dark rays run from the inside to the outside of the iris.

These rays are muscles that open the iris. Other circular muscles close the iris when light gets bright.

LOOK AGAIN

Find the diagram of the eye in the See! Section of the 3VI CD-ROM.

How does the eye change when light gets brighter?

FINISH THIS STATEMENT

When the light gets brighter my pupil grows ___________________________

Why do you think the pupil changes like this?

Note as many reasons as you can.

__________________________________________________________

__________________________________________________________

__________________________________________________________

----------------------------------------------------------

Unit One See! Now You See It

Working with a partner, students make a chart and demonstrate the existence of a blindspot.

Resources

Paper (half A4)

Texta

Measuring ruler

3VI CD-ROM (optional)

Student Activity Sheet See! Now You See It

Materials

Paper

Texta

Measuring ruler

Draw and colour in black a circle 1centimetre across.

Near the left-hand side of the paper, colour a small dot (half a centimetre to 1 centimetre across.)

Near the right hand side, put a cross about the same size.

Hold the piece of paper out in front of your partner.

Your partner closes their left eye and looks at the CIRCLE with their right eye.

Brings the paper SLOWLY towards your partner ’s face.

Get your partner to tell you when the CROSS disappears.

WHY DOES THIS HAPPEN?

Take another look at the diagram of the eye in See! Section of the 3VI CD-ROM.

Notice how the eye is joined to the brain with an OPTIC NERVE.

The spot where the OPTIC NERVE grows out of the RETINA is our blind spot.

The cells on the blind spot don’t get excited by light.

When the light from the cross hits your blind spot, you don’t see it – it disappears!

Why do you think you might not usually notice this?

__________________________________________________________

__________________________________________________________

__________________________________________________________

__________________________________________________________