Making light bounce involves redirecting a beam of light. This project requires three or more mirrors, a flashlight and a book. Turn the lights off in your classroom, and close any shades to make it as dark as possible. Stand a book up on a table, then point the flashlight at the front of the book and note what happens. Lean a mirror against the front of the book; this time, point the flashlight at the mirror. Note the change in the beam of light. Use several more mirrors in different locations on the table to direct the beam of the flashlight to other positions.
Several inventions in the category of light and optics are appropriate for fourth grade students. First, use a prism to see which colors combine to make up white light (sunlight). Hold up a prism in the sun, and note the colors reflected on the ground. (White light comprises six colors: red, orange, yellow, green, blue and violet.) Put another prism in the reflection and observe the light coming back together. Students will also enjoy making a chart listing the different uses for a magnifying glass and recording how each one uses the lenses and light for different applications, such as binoculars and a microscope. Finally, research and develop a chart on the reasons for using different colored lights on emergency vehicles.
Incident light is the direct light that falls on a surface. For this invention using incident light, students need a music stand, a solar cell, a source of white light, a multimeter and a protractor. Attach the solar cell to the music stand, and adjust the solar cell to different angles. Measure the amount of milliwatts produced from each angle using the multimeter.
Germination occurs when seeds have the right amount of light, heat and water. To see how light affects the speed of germination, students can invent a type of germination measuring tool. To do so, students will need three transparent plastic containers with transparent lids, some paper towels, water, two cardboard boxes just a little bigger than the containers and some seeds. Punch five holes in one of the walls of one cardboard box. Cover the holes with a thin sheet of white paper to prevent the seeds from receiving direct light. Put a layer of paper towels on the bottom of each container, and add water until the towels are wet. Put equal amounts of seeds in each container, then put the lids on. Put one container in the open box, one container in the shaded box and one container in the light-proof box. Using the open box as your control group, watch until all seeds develop roots and green leaves. Open the shaded box and the closed box and compare the plants, making notes in a journal about size, color and root structure. Use this invention on other types of seeds to see whether the results remain the same.