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teachwire.net/secondary 95 ADDITIONAL RESOURCES Some scientists have suggested that our imaginationsworkbest in the dark.Research published in the Journal ofEnvironmental Psychology [Steidle,A.,& Werth,L.(2013) – 'Freedom fromconstraints: Darkness anddim illumination promote creativity'; Journal ofEnvironmental Psychology , 35,67-80] looked at the difference in creativity levels between brightly lit and dimly lit environments,and found that when the lighting was dimmed,peoplewere morewilling to explore and take risks and felt freer from constraints.Whynot askthe students to test this theory whenwriting their stories? 1. The chemistry of colour Ask your students if they believe clothes stored in a dark wardrobe are still coloured. To properly answer this seemingly simple question, we need to consider the physics of light and the chemistry of dyes and pigments. The dyes and pigments contained in an object or fabric are chemicals that absorb light of a very specific energy in the visible region of the spectrum. This is linked to the wavelength by the following formula: Where E is the energy, h is Planck’s constant, c is the speed of light and λ is the wavelength. As your students will have already discovered using Newton’s prism, different colours of light have different wavelengths. It follows that the chemicals in the dyes used in the clothes will absorb some wavelengths of light, but not others. What we’re seeing when we look at them is the light that’s left over; scientifically referred to as ‘transmitted’ or ‘reflected’. An object that absorbs red light, for example, will appear green. In our dark wardrobe there is no light to be absorbed, and therefore no light can be transmitted – which means that the clothes are not coloured! Some chemicals that absorb light in the visible region of the spectrum are rare and special, but others have been around for hundreds of years. Indigo, for example, was used in Britain during Roman times – now it’s used to colour blue jeans. Students could carry out a microscale synthesis of indigo dye using the method provided by the Royal Society of Chemistry (see bit.ly/ ts-microscale). Extend the practical to tie-dying a T-shirt, by dissolving precipitated dye in an alkaline solution of sodium dithionite and soaking the fabric in this colourless solution. Once soaked, the T-shirt can be unwrapped and exposed to air to produce indigo-dyed fabric. 2. The biology and psychology of colour We perceive different wavelengths of light as colours using cone cells on the retina. Some of these respond to red light, others to green and others to blue. The resulting signal travels along the optic nerve to the visual cortex of the brain, which translates the signals into colours. Show your students the short TedEd talk, ‘How we see color’, (see bit.ly/ted-how-colour ) to help them understand this. Keep the students focused by asking them to complete a worksheet of comprehension questions during the video. An interesting phenomenon is how these different MAIN ACTIVITIES wavelengths are often linked with specific feelings. Who hasn’t described ‘feeling blue’ when sad or lonely, or linked red with anger? Encourage your students to carry out their own research by compiling some simple clipart pictures that can be modified with a single colour and asking some straightforward questions. This could be done using Google Forms to collate the data and generate bar charts showing the most popular responses, enabling your class to see if they associate different colours with different characteristics. Below are some example questions, inspired by research recently published in the Journal of Experimental Psychology [Kramer, R., & Prior, J. (2019) – ‘Colour associations in children and adults’; Quarterly Journal of Experimental Psychology , 72(8), 1977-1983]. GOING DEEPER Encourage students to link their scientific understanding of colour, light and emotion to literacy by writing a piece of extended creative writing. Ask them to focus on describing colour and light in the narrative to recreate the mood of their story. THE AUTHOR Dr Joanna Rhodes M.Chem, D.Phil, MRSC is Head of Sixth Form at Wakefield Girls’ High School • Which boy is cleverest? • Which boy is happiest? • Which boy is strongest? • Which boy is most honest? • Which boy is naughtiest? • Which car is fastest? • Which car is slowest? • Which car is safest? • Which car is the most dangerous? • Which car is the most expensive? • Which cat is the happiest? • Which cat is the angriest? • Which cat is the unluckiest? • Which cat smells the worst? • Which cat is coldest?