To complete this project, you'll need four identical desk lamps, all containing the same wattage of bulb. You'll also need to prepare four different same-sized squares of cardboard, such as 10 inches by 10 inches. Use four different colors, including white and black, to test the biggest range of colors. Finally, you'll need four identical thermometers and an adhesive, such as tape or white tack, to stick the thermometers onto the backs of the cardboard squares and finally, you'll need a clock or timing device.
Set up the four squares of cardboard in a dark room so that they stand upright --- using a dark room ensures that the cardboard is not influenced by natural light. Set up a desk lamp immediately in front of each cardboard square and train the light so it shines at the same distance and angle from the cardboard, ensuring that each colored cardboard is tested in the same way. Affix a thermometer in the center of the back of each piece of cardboard, so it is on the opposite side of where the desk lamp is pointed at the cardboard squares.
To start your experiment, switch on all four of your lights and start your timing device. Check the reading on each thermometer once every 5 minutes and note the temperature, making it clear which color of cardboard you are recording the temperature for. Continue this procedure for at least 1 hour so you can see how the different colors of cardboard affect the temperature reading on each thermometer. Take at least one photograph of each cardboard square, but make sure you do not let the flash go off because this will disrupt the square's exposure to light and heat.
Set up your science fair display, including your photographs of the experiment setup. You should also plot graphs of your findings, which will show that darker colors absorbed more heat, and so reached a higher temperature. Plot a line graph with time in 5-minute intervals on the x-axis (horizontal) and temperature in Fahrenheit on the y-axis (vertical). Represent the colors used in the experiment on the cardboard squares for the lines on your line graph, as the black line climbs most steeply while the white line will be much more shallow. Accompany your photographs and graph with a spoken presentation about which colors attract more heat and how, for example, consumers could paint their houses black to make it warmer, which would lower their heating bill and their carbon footprint.