Learners are challenged to create solutions that conduct electricity and make a buzzer buzz (or an LED light up). They are given water, salad oil, alcohol, and vinegar as liquids, salt and sugar as solids, and a conductivity tester to see which combinations conduct electricity. Some liquids conduct by themselves (vinegar), and others can be made to conduct when salt, but not sugar, is added. The chemical explanation is that positive and negative particles called "ions" make solutions conductive. Depending on the age of learners, this activity may require constant supervision of all materials and steps. Instructions are provided for building simple conductivity testers, or these can be purchased.