Children can find out what ingredients clean pennies most effectively, Parenting explains. The child needs to get several dirty or tarnished pennies and cover them in various ingredients, including taco sauce, vinegar, tomato paste, salt and water, using one ingredient at a time. After finding out that none of the ingredients work well to clean the pennies, the child can then combine ingredients until he finds the winning mixture.
Another elementary science project is to observe the chemical reaction between Alka-Seltzer and water, says Parenting. The child needs to wear safety glasses before placing one-fourth of an Alka-Seltzer tablet into an empty film canister filled halfway with water. She should observe the reaction, then she needs to try the experiment again. This time, she needs to place the lid on the film canister and observe the reaction. The lid should shoot into the air. The child needs to step back during this last reaction to avoid getting hit.