In Feel the Heat, students follow the engineering design process to build a solar hot water heater and redesign their device to see how big a temperature change they can get by changing different variables. The phenomenon of energy transfer can be a challenging concept for upper elementary students, however, this activity provides the students with the opportunity to use their investigation data to improve their heater to increase the temperature of the water. This lesson contains elements that are appropriate for middle school(convection/conduction/radiation), but the basic premise of the lesson, that solar energy can be used to heat water, is appropriate for upper elementary. Teachers can decide to use a gooseneck lamp with an indoor 100-watt floodlight as the energy source for the student water devices (safely precautions tips included), or they can choose to work outside with the sun as the natural energy source.