3. Additional text for independent work Colour Blindness

Colour blindness is an inaccurate term for a lack of perceptual sensitivity to certain colors. Absolute colour blindness is almost unknown, but in very rare cases, total colour blindness occurs. Colour blindness can happen in one of two ways:

Typical: Complete inability to discriminate between any colour variations, which is usually associated with other severe vision impairments.

Atypical: The ability to only see very clear colours.

Affecting around 7% of men and around 0.04% women, the main form of colour blindness is the inability to distinguish red from green. This means that people affected do not see the colours red and green the same way as others. The cause of this is due to the red or green photoreceptors working incorrectly.

Rods and Cones

Our eyes contain what are called rods and cones. It is these rods and cones that give us the ability to see colour.

The rods deal with brightness and the cones with colour. There are three different types of cones: red cones - green cones and blue cones. People that are effected by colour blindness, have less numbers of particular cones than normal, so they get colours confused. They may be able to see a bright green coloured object outside, but when viewed in artificial light, the same object may appear brown in colour. Or if the object was a dull green, it could even appear red.

Take a look at the two images below: Fig.15

People with normal colour vision and those with all colour vision deficiencies should read the number 12. People with normal colour vision should see the number 8. Those with red-green colour vision deficiencies should see the number 3. Total colour blindness should not be able to read any numeral.

APPENDIX 3

1. Grammar Summary

In English, tenses are formed by conjugating an auxiliary verb plus a standard form of the principal verb (the base form, the gerund form, or the past participle form). It is import to focus on the variations in the auxiliary verb to properly use English tenses.

Symbols Used:

S (subject) Aux (auxiliary verb) O (objects) ? (question word, i.e., who, what when, etc.)

Construction:

In general, using the following patterns to construct sentences in active sentences.

Positive: S + Verb + O Negative:S + Aux + Verb + O Question:(?)+ Aux + S + Verb + (O)

Future with 'Will'

Use the future with 'will' to:

• Make a future prediction

• Express a decision made about the future at the moment (spontaneous reactions to events)

• Make a promise

• Think about future possibilities

Examples:

It will rain tomorrow. I think he won't attend the meeting. Oh! You're all wet. I'll fetch you a blanket.

Future with 'Going to'

Use the future with 'going to' to speak about future intentions or plans made before the present moment.

Examples:

We are going to study abroad next semester. Who are you going to visit in Seattle? Peter isn't going to attend next week's meeting.

Future Continuous

Use the future continuous to speak about an activity that will be happening at a precise point in time in the future.

Examples:

I'll be playing tennis at four this afternoon. When you arrive in Boston, I'll be sleeping soundly in my bed. What will you be doing this time next week?

Future Perfect

Use the future perfect to express something that will have been done up to a precise point in time in the future.

Examples:

She'll have read the book by the time you arrive. I'm afraid we won't have finished by the end of tomorrow afternoon. What will you have studied by the time you finish college?