In this lab, students write hypotheses and procedures as they investigate how temperature changes during a phase change. This lab identifies a major misconception. Students believe that adding heat to water will always increase its temperature. In this lab, they learn that they can add heat and the temperature will remain constant during a phase change such as melting or boiling. This is an inquiry lab so a lab procedure is not given. Students use their own ideas to answer questions about what happens to temperature during melting or boiling.