Here are photos and general instructions for demonstrating two oxidation reactions with your physical science beginners. They use salt and hydrogen peroxide to cause iron filings to rust, and they combine hydrogen peroxide with a piece of steel wool as well. The steel wool has a strong enough reaction to give off heat, so it also serves as an example of an exothermic reaction. Note that exact amounts for each material are not provided, so you may want to prepare a few more detailed instructions for your class.