Learners work in teams to design and build solar water heating devices that mimic those used in residences to capture energy in the form of solar radiation and convert it to thermal energy. This thermal energy is next transferred to water (to be used as domestic hot water) in the form of heat. In doing this, learners gain a better understanding of the three different types of heat transfer, each of which plays a role in the solar water heater design. Once the model devices are constructed, learners perform efficiency calculations and compare designs. Note: part of this activity must be conducted outdoors on a sunny day (it is okay if it's cold, but it must be sunny).