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Misconceptions: Colour and Vision

see Colour
Misconception Discussion of the problem Possible Activities
The pupil of the eye is a black object or a spot on the surface of the eye. Idea it is the gap in the centre of the iris. Observation of how the pupil changes size in different light intensities (Care they don't blind each other!) Discuss eye exams in an optician - how s/he looks through the pupil
The eye receives upright images on the retina. Ray diagrams can be used to show how the image is inverted Use vid-clips to show full visual sytem
The lens is the only part of the eye responsible for focusing light. Cornea is primary refractor Discuss sight correction using lasers - resculpting of the cornea - use a glass ball to refract light.
The lens forms an image (picture) on the retina. The brain then "looks" at this image and that is how we see. Correct terminology for image interpretation needs to be reinforced Use vid-clips to show full visual sytem - discuss how blindness can happen to people with perfect eyes
The eye is the only organ involved in sight; the brain is only for thinking. Correct terminology for image interpretation needs to be reinforced Use vid-clips to show full visual sytem - discuss how blindness can happen to people with perfect eyes
A white light source, such as sunlight, an incandescent or fluorescent bulb, candle flame etc. produces light made up of exactly the same spectrum of colours. Spectra of sources differ according to the electron transitions involved

Use a series of light sources and compare the spectra or what stips of multicoloured cloth look like under them - discuss how clothing looks different under different light sources.

Could look at spectra from stars...

When white light passes through a coloured filter colour is added to the light. Filters subtract Use multiple filters
The rules for mixing color paints and crayons are the same as the rules for mixing coloured lights. So the primary colors for mixing coloured lights are red, blue and yellow.    
A colored light striking an object produces a shadow behind it that is the same color as the light. For example, when red light strikes an object, a red shadow is formed. Comics are to blame for this! Demo
The shades of grey in a black and white newspaper picture are produced by using inks with different shades of gray.   Use a magnifying glass to look at the dots
The different colors appearing in coloured pictures printed in magazines and newspapers are produced by using different inks with all the corresponding colors.   Use a magnifying glass to look at the dots
Colour is a property of an object, and is independent of both the illuminating light and the receiver (eye).   Look at coloured objects under different coloured light sources.
White light is colourless and clear, enabling you to see the "true" color of an object.    
When a coloured light illuminates a coloured object, the colour of the light mixes with the colour of the object.    
Explanations of visual phenomena involving color perception usually involve only the properties of the object being observed, and do not include the properties of the eye-brain system.   Talk about colour blindness - use colour blindness tests.