The topic of a science fair project does not significantly contribute to its ability to win. Rather, it is the manner in which the project is performed and presented that wows the judges and garners the blue ribbon. Take an original, thoughtful and detailed approach to your subject, and present it in a clear, eloquent and eye-catching way: this is the key to success. Some areas of science may be slightly more conducive to this approach in seventh grade.
Many factors can affect the growth of plants: the ambient temperature, additives in the soil or water, the amount of light received and the chemical composition of the plant itself. A science fair project can test any of these factors, either comparing their effects on different types of plants or determine which one has the most effect on a specific plant's growth or germination. Alternatively, you could simulate a real environmental occurrence, such as acid rain or oil pollution, and demonstrate how this event detrimentally influences plant growth and how we can fix it.
Every day, you are bombarded with advertising claims. Some winning science fair projects test these claims, comparing the true effectiveness of various competing brands. For example, you could construct an experiment to see which batteries really last the longest, which paper towels really absorb the most liquid, which cleaning products kill the most germs or which cheese, bread or milk molds fastest. You could also see how quickly different brands of painkillers dissolve, or test different brands of sports equipment, such as golf balls or baseball bats, to see if they improve a player's performance.
With so much concern about the cost of energy and the threat of global warming, environmentally friendly practices are becoming more of a national interest. Put your project on the cutting edge by researching the factors that affect the efficiency of solar panels or comparing the various types of renewable energy. Document how much your school or community recycles and report on ways to improve this data. Test different oil absorption materials to determine how best to clean up oil waste, or demonstrate the differences between growing food organically or not.
Boys vs. Girls
The differences between boys and girls are often the subject of ridicule in seventh grade, but you can put these notions to the test in a science fair project. Pick a skill to test, such as memory, strength, reading speed, blood pressure or reaction time. Gather a group of male and female subjects and ask them to perform a series of tests that you design to tease out the differences you want to investigate. Try to design the tests in a way that does not let the subjects know why they're being tested.