At Home Chemistry: Cleaning Pennies with Ketchup -- Team Cartwright STEM in action! Learn how to clean pennies using ketchup, and learn the science behind it. A simple kitchen chemistry experiment for preschoolers and kids. Do you think it will work? Science Experiments For Preschoolers, Preschool Science Activities, Easy Science, Stem Science, Science For Kids, Kids Chemistry Experiments, Stem For Preschoolers, Science Art, Chemistry For Kids