Does the change in energy of matter lead to a change in mass? Upcoming chemists compare the mass of equal-volume, but different-temperature liquids and materials both before and after a chemical reaction has occurred. In another activity, they examine product labels to find commonly used elements and compounds. They use zinc and sodium hydroxide to change the chemical makeup of a penny. These activities, though pertinent to chemistry, are only slightly related to each other. You may want to use some and not others depending on what concepts you are teaching.