Science Fair Ideas: Projects that Use Plants

It's about time for the annual middle school science fair to roll around, and you would really like to help your young student put together a first-rate project that will provide an educational opportunity....oh, and impress the judges as much as possible. Moving on from the tired old clay volcano and lemon battery projects, you will probably discover that a worthwhile science fair project takes a bit more preparation time. In other words, the better science fair projects probably can't be started and completed on the night before the due date, even if you do stay up until 2 AM to get it done. If you start far enough ahead, however, you may be able to come up with a project that will actually hold your student's interest, to the extent that you can sit back and watch, and maybe offer a few suggestions from the sidelines.

Plants (both seeds and seedlings) make excellent subjects for science fair projects. They respond in different ways to various stimuli. They are easy to acquire, and they are inexpensive. Having been both a biology teacher and a science fair judge in the past, I always appreciated projects that were based on plant life, for two main reasons. a) It usually proved that the project had to be given some thought ahead of time (planning), and b) there was an investment of time on the part of the student, perhaps as much as several days or weeks.

There are many different science fair project ideas that involve plants, some that are appropriate for younger students, and some for the higher grades. The examples discussed below may serve as the basis for your own "non-volcano" project for this year's school science fair.

1. Speed of Seeds. For this science fair project, collect a variety of vegetable and/or flower seeds from the garden store, and see which tends to germinate the quickest. Obviously, you will want to eliminate as many variables as possible. Therefore you will need to plant all of the seeds at the same depth in the container of growing medium or potting soil, provide each container the same amount of water, set each container in the same window area (temperature control), etc. Select about five or six garden vegetables to monitor, such as radishes, corn, beans, peas, etc. Make a chart with each type of plant, and record the number of days that each takes before a sprout starts to show up. Repeat the test a few times to see if you get the same results each time. Then add a follow-up test by repeating the test, but this time, soaking the seeds overnight before planting, and see if the results change. If they do, ask the student to explain what they might have learned about the germination process, seed coverings, planting methods, etc.

2. Gravitropism. Start several tomato plants from seed, or buy small plants already up and going. The variables for this science fair project are a little less important than in other experiments. As long as you have several healthy plants, the size of each one is not really significant for this test. Placing all of the plants in individual pots, set half of them in the normal position, roots down and leaves up, and set the other half of the plants in a horizontal position. Keep the plants watered lightly, and watch for the horizontal plants to demonstrate gravitropism, the inclination of the plant to correct itself relative to gravity. Take a picture each day to track the speed of the change, and post them on your science fair project display board in the appropriate sequence.

3. Allelopathy. Some plants actually give off a chemical limiting the growth of other plants in the same area, in order to control the competition for water and nutrients in the soil. The process is referred to as allelopathy. The list of allelopathic plants includes sweet potatoes, sunflowers, black walnut trees, alfalfa and others. Considering the ease of growing sweet potatoes, create a science fair project where three different types of containers are used. One container would contain only a mixture of radish and bean seeds, a second container would include only a sweet potato plant, and the third container would both the sweet potato and the mixture of bean and radish seeds. Determine if the growth of the radish and bean seeds is healthier in the container that does not include the sweet potato plant.

4. Transpiration. Have your student learn about transpiration, the movement of water through the plant from the root system, and out through openings on the leaves. (This is how plants move nutrients.) For the science fair project, cover four to five leaves on a thin-leaf house plant, such as a philodendron, with a plastic sandwich bag, and set the plant in the sun. After a period of time, check the bag at regular intervals for the presence of water droplets. For the next phase, place the bag over the leaves of a succulent plant, such as jade or aloe vera, and see if there are fewer droplets forming. Study the purpose of the thicker skin for such water-preserving plants, and where they may be found in nature. For a third phase, place the bag again over the thin-leaf plant, and intensify the light source. Determine if an increase in heat is equivalent to an increase in the transpiration rate. Make sure that the root system of each plant is provided with adequate water during the experiment.

Perhaps in the development of these science fair project ideas, your young scientist will ask questions of his/her own about how plants function. If you find those questions to be good ones, allow him to design a science fair experiment that will prove the hypothesis. Be sure to document your daily results/discoveries, and show everything in proper sequence when preparing your final display. Actual plants should be used in the display to provide a sense of authenticity, but photographs of the plants at various stages may also help to tell the story.

I would offer one last bit of advice, regardless of whether you do a botanical science fair project, or some other kind. Start early. Plan well. Make sure that you and your child enjoy the learning time together while preparing for the science fair. Completing an experiment on schedule or ahead of schedule is so much more pleasant than the stressful situation of trying to do everything the night before the science fair opens. (Follow the voice of experience in this matter.) Now head out to the seed store before the science fair gets here!