- I can use accurate terminology to talk about images that represent energy transfer, storage, and use.
- I can follow the transfer of energy through a system; for example, by making a flow chart or other diagram.
- I can describe different technologies and engineering solutions for capturing, storing, and using energy.
This information is not for classroom content, but to prepare teachers for the photographs, activities, and potential questions from students.
A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas (p. 128–29) has background material for these activities:
In ordinary language, people speak of “producing” or “using” energy. This refers to the fact that energy in concentrated form is useful for generating electricity, moving or heating objects, and producing light, whereas diffuse energy in the environment is not readily captured for practical use. Therefore, to produce energy typically means to convert some stored energy into a desired form—for example, the stored energy of water behind a dam is released as the water flows downhill and drives a turbine generator to produce electricity, which is then delivered to users through distribution systems. Food, fuel, and batteries are especially convenient energy resources because they can be moved from place to place to provide processes that release energy where needed. A system does not destroy energy when carrying out any process. However, the process cannot occur without energy being available. The energy is also not destroyed by the end of the process. Most often some or all of it has been transferred to heat the surrounding environment; in the same sense that paper is not destroyed when it is written on, it still exists but is not readily available for further use.
Naturally occurring food and fuel contain complex carbon-based molecules, chiefly derived from plant matter that has been formed by photosynthesis. The chemical reaction of these molecules with oxygen releases energy; such reactions provide energy for most animal life and for residential, commercial, and industrial activities.
Electric power generation is based on fossil fuels (i.e., coal, oil, and natural gas), nuclear fission, or renewable resources (e.g., solar, wind, tidal, geothermal, and hydro power). Transportation today chiefly depends on fossil fuels, but the use of electric and alternative fuel (e.g., hydrogen, biofuel) vehicles is increasing. All forms of electricity generation and transportation fuels have associated economic, social, and environmental costs and benefits, both short and long term. Technological advances and regulatory decisions can change the balance of those costs and benefits.
Although energy cannot be destroyed, it can be converted to less useful forms. In designing a system for energy storage, for energy distribution, or to perform some practical task (e.g., to power an airplane), it is important to design for maximum efficiency—thereby ensuring that the largest possible fraction of the energy is used for the desired purpose rather than being transferred out of the system in unwanted ways (e.g., through friction, which eventually results in heat energy transfer to the surrounding environment). Improving efficiency reduces costs, waste materials, and many unintended environmental impacts.
Begin the Activity
In small groups or pairs, have students choose a photo to examine, and explain how energy is being captured, stored, or transferred in the system in the photograph. Students should discuss the state of the energy and the system before and after the situation shown in the photo. (Note that this exercise is mainly designed for high school students, so middle school students might use less sophisticated terms. High school students with more science experience might use more advanced terms. For example, they might discuss if they are seeing the capture of kinetic energy, or the release of chemical bond energy as heat.) In small groups or pairs, have students select a series of related photos and assemble them to portray a designed energy system. If the photos are not adequate to show a complete system, have the students identify the missing step. Remind students to try to use words that emphasize transfer and conservation of energy in the universe, rather than terms that suggest creation, generation, or loss of energy.
Have students make a diagram—for example, a flow chart or systems diagram—that shows the transformation of energy in each photo.
Questions to Consider
Engineers work to design practical solutions to real-world problems by breaking them down into smaller, solvable problems. Spend a few minutes thinking like an engineer, considering a solution to a problem based on priorities and thinking about trade-offs and limitations. Use this type of thinking to describe ways that humans do or could take advantage of the energy source shown in one of the photographs and use it to do work.
- How could the energy source be tapped and what could it be used to do?
Systems developed for capturing energy from a particular source often have similar design elements; however, the designs for individual energy-capturing systems vary, depending on a variety of factors.
- For photographs that show a mechanism designed to harness an energy source, how could elements of the mechanism be used to harness a different energy source? (What design elements do windmills and waterwheels have in common, for example?)