One easy science experiment for preschoolers involves layering several liquids in a tall glass or graduated cylinder to demonstrate the concept of density. Another simple experiment requires making and microwaving a flour-based paint to produce three-dimensional pictures.
To conduct the density tower experiment, kids need to pour liquids of varying densities into a tall cylinder one level at a time. A sample list includes honey, corn syrup, maple syrup, milk and dish soap, but if the container is tall enough, kids can also add tap water, vegetable oil, rubbing alcohol and lamp oil. About 50 to 100 milliliters of each liquid must be poured slowly and carefully into the cylinder's center, allowing the liquid to spread and level out gradually.
Kids can also compare the densities of different objects by dropping in small items, such as a bolt, soda cap, plastic bead and popcorn kernel. The objects settle on different levels, depending on their density.
In the puffy paint experiment, kids mix self-rising flour with salt and add water to produce paste. Blending food coloring into each paste mixture allows kids to create their preferred colors, and they should use the homemade paint on heavy paper, such as cardstock. By placing the paper in the microwave for roughly 30 seconds, children can watch their painted designs puff up.