Two commercial self-heating food products have been used to apply chemical concepts such as stoichiometry, enthalpies of reactions and solutions, and heat transfer in a classroom activity. These products are the self-heating beverages sold in Europe and the Meals, Ready to Eat or MREs used primarily by the military in the United States. The main goal of the activity is to propose a real-life chemistry problem for which students calculate the heat produced by the chemical reaction or the dissolution process, the accompanying theoretical change in temperature, and finally compare the theoretical change to the temperature observed. The activity is designed to use five minutes of class time and allow students to work in groups, outside the classroom, to solve the posted problems. We have used two different methodologies with this activity: problem-based learning and inquiry-guided instruction. The context of these activities connects a variety of chemistry topics and provides the opportunity to practice common operations such as unit conversion and algorithmic problem solving in the context of a real-world scenario. The key element is the evaluation process that students must conduct at every stage, which includes examining food products promotion information. (Contains 2 figures.)