Third graders learn about renewable and nonrenewable sources of energy. Renewable sources of energy include wind, solar, water, geothermal and biomass. Oil, coal and natural gas are nonrenewable sources of energy. Students may also learn about batteries, electricity and food as sources of energy they use everyday. Energy cannot be created or destroyed but transfered from one form to another. For example, heat energy released from burning coal and kinetic energy from flowing water are used to power turbines that generate electricity. Electric current releases heat energy when it flows through a circuit to power a light bulb.
Investigate the amount of electricity your household uses and the efficacy of energy-saving techniques. Energy-saving strategies include turning off lights when you leave a room, unplugging electrical devices when not in use, lowering the thermostat in cool weather or raising the thermostat in warm weather and reducing or eliminating TV viewing or computer usage. Calculate your household electricity usage for two weeks by reading at the beginning and end of the two-week period. Test an electricity-saving strategy for two weeks and calculate meter readings at the beginning and end of the test period. For a more complex project, choose a second strategy to test for another two-week period and then compare the results to find out which strategy resulted in lower energy usage.
Electric current generates heat. Light bulbs convert electrical energy to heat energy. Light bulbs give off heat. Find out how much heat different wattage light bulbs release. Use four different lamps and clip or tape a thermometer to the base of each lamp. Alternately, place a thermometer on a table directly in front of each lamp. Choose a different wattage bulb for each lamp, including an energy-efficient bulb, such as a compact fluorescent bulb (CFL) or LED bulb, if possible. Record the temperature while the light is off, then turn the lamps on and record the temperatures after two or more intervals. Chart the results to determine which bulb gives off the least or most heat.
Students can use solar energy to heat water or cook food using reflective or insulating materials, depending on the device they construct. Solar energy heats a cup of water or cooks a hot dog in a solar oven made from a box equipped with a reflective panel and lined with aluminum foil. A solar batch collector heats water in an insulated container. You can make your own by placing water in a garbage bag and setting the bag on an insulation panel. Secure a thermometer in each sample of water tested for either method. Experiment with different materials and construction techniques to find out which device heats water fastest or to the highest temperature. Other variables to test include color of the bag or box, amount of water and sunny versus cloudy conditions.
A science fair project should follow the scientific method for setting up an objective, repeatable experiment with at least one variable and a control. Rather than reproduce an experiment you’ve already learned about, try to think of an original question and design an experiment to help you answer it. Collect and record observations, describe results, draw conclusions about the results and share your findings. Also, consider the amount of time and money you need to complete the project. This includes the cost of materials and the time needed to conduct the experiment and analyze the results, construct models, if necessary, and prepare the presentation of your project.