4. Chemical Link with Invisible Ink

STEM activities for afterschoolTrain students to be scientists–and potential super spies–through your STEM activities for afterschool programs, such as this project from Scientific America that helps kids create invisible ink. Each student must have one half of a lemon, one half teaspoon of water, a small bowl, spoon, white paper, cotton swabs, a heat source such as a lamp or radiator, and a pencil. After mixing juice from the lemon with water, use a solution-soaked cotton swab to write a message on the paper and wait for it to dry. Then have students hold the paper up to the heat source. The visible message is the result of chemical reactions that cause carbon to oxidize.