Science fair project ideas that use water include tracking how water moves through the root of a plant or determining if boiling water removes all contaminants. Students can also measure if ice melts at a rate proportional to its surface area.
Another science fair experiment using water is measuring how much water dried beans absorb. To perform this experiment, students begin by labeling six plastic cups "Zero," "20 Minutes," "One Hour," "Three Hours," "Nine Hours" and "27 Hours." Weigh the beans in the first cup. Add 100 milliliters of water to cups two through six, and record the time. After 20 minutes, drain the water from the second cup, dry the beans with a paper towel, and measure their weight. Repeat for cups three through six at the appropriate times. Students can graph the results to display their findings.
Students can also experiment with adding chemicals to water changes its freezing point. They can perform this with saline or sucrose solutions, and they should use pure water as the control. Pour each solution in a test tube, place the test tube in an ice bath, and check it every five minutes until ice crystals start to form. This is the freezing point of the solution. Use a thermometer to measure the temperature, and record the data. Repeat with different strength solutions.