Addresses AP® Chemistry Big Idea 3 and Learning Objective 3.3. Determine the molar ratio of reactants in 2 acid-base reactions using the method of continuous variation. React acid and base in different ratios and graph the temperature changes. The volume ratio that produces the largest temperature change is the correct reaction stoichiometry. Students design a procedure to collect data, plot data, calculate molar ratios, and write chemical equations. Materials are sufficient for 30 students.