Common devices such as the iron or a hair dryer work through the conversion of electricity into heat. Your child can experiment on whether the process can be reversed and if he can transform heat into electricity. In order to convert heat into electricity, your child builds a thermocouple using two metals such as alumel and chromel or iron and constantan. Place a heat source and use the thermocouple to translate the heat into electricity. A voltmeter is necessary to test if electricity is produced.
Saltwater can function as an electrolyte and power a light bulb. Your child needs a low-voltage light bulb and a base for it, as well as insulated copper wire, alligator clips, magnesium and iron electrodes and a cup of saltwater. Link the wire to both electrodes and the screws from the base of the light bulb. Insert the electrodes in a cup of saltwater and the bulb should light up. Your child can experiment with different concentrations of salt to observe if there are variations in the light intensity or even use different minerals instead of salt to find if there are any possible replacements.
Your fifth grader may be aware of the project that involves using a potato instead of batteries to power an LED clock. This project requires two potatoes, copper wire, two galvanized nails, alligator clips and an LED clock without batteries that typically functions on 2-volt batteries. Since the potato works as an electrolyte or an electrochemical cell that converts chemical energy into electrical energy, your child may experiment with limes, onions, bananas, apples or other fruit to determine if these work to replace the potatoes. This is a safe, uncomplicated project and your child may look for the cheapest or smallest fruit or vegetable that can work as an electrolyte.
Your child can prepare a project using photovoltaic panels to power a motor that puts a fan or a different device in motion. Your fifth grader may experiment with changing the angle of the solar panel to observe its effects on the speed of the fan. As an additional experiment, your child can place mirrors, windows or different types of lenses in the proximity of the panels to concentrate light and increase the efficiency of the photovoltaic panels. This project can teach your child about the numerous possibilities of using solar energy and a few methods to make the system more efficient.