Students in grade 8 have been studying temperature, thermal energy, and heat. In this lab, students put rock salt on an ice cube and measured the temperature of the melted water every minute for ten minutes. They found that the resulting water attained sub-zero temperatures. This is because the dissolution of salt in water is endothermic and because the dissolution lowers the freezing point of water causing less liquid molecules to attach to the ice lattice (freeze). This lab demonstrates heat transfer and allows students to gain practice measuring temperature. Practically speaking, this explains why salt is used to “melt” ice on the roads in winter.