Preschoolers won't understand complicated science, but they can create projects that demonstrate scientific processes. A sun painting is one of these. Have children cut out shapes from construction paper and place them on top of a sheet of black construction paper. They can also use different-shaped objects from around the home or classroom. Leave the papers out in the sun for several hours. Have students predict what might happen to the black construction paper before returning to observe them. The darker paper will lighten in the sun so that the silhouettes of the shapes placed on top of them will become visible. Discuss with the students why this happened.
Magnets can be the basis for all types of science projects. These projects can range from very simple to very complex. A simple, yet educational, project for kindergartners is simply exploring materials to see which ones are magnetic and which ones are not. Have students make predictions about which materials will be attracted to a magnet and which materials will not exhibit any attraction. Then give the students magnets and let them test their predictions, recording when they were correct and when they were incorrect. Have students try to describe what types of materials were magnetic. This can lay the foundation for much more involved projects and experiments.
Several science projects also make use of eggs. A simple science project for first graders is adding salt to water to make it float. A raw egg will sink in water. Have a student demonstrate this. Next add a teaspoon of table salt to the water and see if the egg still sinks. Repeat the process until the egg floats. Have students record how much salt was added to a specific volume of water to make the egg float. This happens because the salt water becomes more dense than the egg.
A more advanced magnet-based science project is to actually create a magnet. Start with a sewing needle or stick pin and a permanent magnet. Stroke the needle along one side of the magnet 30 or more times. Be sure to have the students only stroke the magnet in one direction. This process will magnetize the needle. Students should check the needle against magnetic materials to ensure that the process worked and to see how strong the new magnet is.
Another way to make a magnet is to create an electromagnet. Coil insulated copper wire around an iron nail. Make sure to only wrap the coils in one direction. Strip a small amount of insulation from the ends of the wire and attach those to a D-cell battery. This creates an electromagnet. Try increasing the strength of the magnet by adding more coils to the wire or by adding more batteries.
Fourth graders are ready to perform several projects and experiments. One idea is to compare how effective sunscreens of different SPF levels are. Buy photo-reactive paper from a science supply store. You will also need a sheet of clear acetate from an office supply store. Cut four sheets of acetate that are about equal to the size of each photo-reactive sheet. Cover three of the acetate sheets with different amounts of SPF sunscreen but leave the fourth sheet untreated. Quickly unpackage four sheets of photo-reactive paper and place them on a cookie sheet. Cover each photo-reactive sheet with a sheet of acetate then put the sheets in direct sunlight until the control sheet -- the one with no sunscreen -- turns white. Bring all the photo-reactive paper in and prepare the photo-reactive sheets according to the package instructions. Compare the results for each SPF level of sunscreen.