You will need small box containers to house the seedlings and block surrounding light. Pint-size milk cartons in groups of five work well. Try the top of a shoebox to act as a tray for all the plants in your trial. You will also need a marker, one package of radish or lima bean seeds, potting soil, clear tape, foil, a hole puncher, protractor, eye dropper, notebook, ruler and graph paper.
Through three separate or simultaneous trials, you will be able to control the amount of light your seedlings are exposed to, as well as the direction it's coming from. This will allow you to gauge the affect on both the speed and direction of growth of your seedlings. Number five milk cartons, add soil to each and plant four seedlings at a depth of around 1 centimeter, taking care to make them all at this level.
Cut off the top of one carton to allow the seeds to grow in regular light. Meanwhile, a second carton will have no holes, forcing them to grow in complete darkness. Carton three should have one hole in the side, carton four two holes and carton five, four holes. At first, you should wrap cartons three, four and five in aluminum foil to avoid any light exposure. After the seedlings in carton one grow to around 3 centimeters, remove the foil and begin recording the length of the stems each day, as well as their angle of growth using the protractor.
This experiment can be done using natural sunlight or lamps. Try using different kinds, such as grow lamps, incandescent lamps and fluorescent lamps. You can also vary the color of the light and the length of the exposure and the brightness of the bulb. For example, you could expose the seedlings to dim light for a long time or a bright light for a shorter time, and see which method creates the fastest growth.