In pairs or small groups, ask students to talk—and possibly write about—what they picture when they hear the word “energy.” Then have the students look at the photos (projected or on handouts) and talk about how the photos represent energy. Have students identify the types of energy involved in each photographed system, and the inputs, processes, and outputs they see. Students might notice energy types, inputs and outputs (such as movement or light), and processes (such as cranks or wheels). Some students might know terms such as kinetic, thermal, or chemical bond energy. Have students brainstorm other examples of systems for capturing and using energy. Depending on the photos used, they might think of traditional or modern windmills, or new methods, such as solar panels.
Emphasize that, at this point, no ideas are considered right or wrong. Some discussion points might be to note the movement energy of water, waves, and wind; thermal and light energy of sunlight; and stored chemical energy in organic matter such as wood. Human metabolism releases stored chemical energy in food. That energy can be used for movement, such as riding a bicycle. A point to raise in discussions is how photographers visually convey energy: for example, how the water photos emphasize waves and motion rather than tranquility.