Solar cooking is a hot topic among many green-living adherents. Kids can hop on the green bandwagon by learning how to build a solar hot dog cooker. You can build a solar hot dog cooker with only a few things: a cardboard box, glue, aluminum foil, a wire coat hanger and poster board. Students cover the surface of the box with aluminum foil and build a parabolic curve to reflect the sun. The coat hanger serves as a rotisserie mechanism with which to cook the hot dog.
Showing fair attendees how the human body can become a battery that generates an electric current will be a sure attention getter. Supplies for this project include copper and aluminum plates, wood, wire, an alligator clip and a DC microammeter. A few simple connections enable kids to set up a scenario where the child's hands on the plates will generate an electric current that is measurable through the microammeter. Children attending the science fair will enjoy trying this experiment themselves.
The thought of bacteria growing in baby food is a stomach-turner. Doing a food safety experiment on baby food can teach a lesson on general food safety, as well as provide a public service to fair attendees who view the data. To do this experiment, kids will need three jars of three types of baby food: a meat, a vegetable and a fruit. Kids use petri dishes prepared with blood agar to measure (in millimeters) the growth of bacteria in the food after it has been out of the refrigerator for varying amounts of time. A large graph should be prepared for the fair in order to display the data.
People often swim and fish in local ponds and streams, but they may not know much about the ecology of the water, especially on a microscopic level. A science fair project that examines and identifies the microscopic lifeforms will be of interest to attendees, as it is relevant to their recreational activities and the ecological health of the community. Kids will need access to a microscope and slides immediately after collecting specimens from water sources. To make the project more complex, children can compare the number of organisms found in a drop of water from one source versus the number of organisms found in a drop of water from another source. Types of organisms can also be compared. Students can identify the lifeforms they see by referring to a chart, such as the one in ATPE's publication "Pond Water Creatures."