Alone, or as part of the intended unit on chemical reactions, this activity allows learners to experience an exothermic reaction. Here, learners add calcium chloride to a baking soda solution and watch the temperature rise! They will also, as an added bonus, see carbon dioxide bubbles and calcium carbonate solid produced! The publisher tagged the unit as appropriate for grades 3 - 8, but it is recommended that this activity only be done with experienced middle school lab classes.