Students evaluate various everyday energy conversion devices and draw block flow diagrams to show the forms and states of energy into and out of the device. They also identify the forms of energy that are useful and the desired output of the device as well as the forms that are not useful for the intended use of the item. This can be used to lead into the law of conservation of energy and efficiency. The student activity is preceded by a demonstration of a more complicated system to convert chemical energy to heat energy to mechanical energy. Drawing the block energy conversion diagram for this system models the activity that the students then do themselves for other simpler systems.
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- International Technology and Engineering Educators Association: Technology
- National Science Education Standards: Science
- Energy is a property of many substances and is associated with heat, light, electricity, mechanical motion, sound, nuclei, and the nature of a chemical. Energy is transferred in many ways. (Grades 5 - 8)  ...show
- In most chemical and nuclear reactions, energy is transferred into or out of a system. Heat, light, mechanical motion, or electricity might all be involved in such transfers. (Grades 5 - 8)  ...show
- Electrical circuits provide a means of transferring electrical energy when heat, light, sound, and chemical changes are produced. (Grades 5 - 8)  ...show
- Next Generation Science Standards: Science
- Construct, use, and present arguments to support the claim that when the motion energy of an object changes, energy is transferred to or from the object. (Grades 6 - 8)  ...show
- Describe at least three examples of how energy is converted from one form to another.
- Demonstrate and diagram the conversion of energy into usable forms using a flowchart.
- State the law of conservation of energy.
- Identify seven forms and two states of energy.
- Identify the forms and states of energy in everyday items as we use them to do useful energy.
For the combustion demo:
- sterno or other heating source
- 250 ml erlemeyer flask with a 1-hole stopper
- pre-heated water (near boiling) in a thermos
- ring stand to hold pinwheel and flask above heating source
- various electrical, mechanical or battery-operated devices (one per group); examples: battery-operated flashlight, shaking flashlight, light-solar panel-LEGO motor set-up, personal heat packet, Genecon generator, hairdryer, glow stick
- Energy Conversion Student Worksheet
Before the Activity:
- Set up the various energy conversion devices around the classroom. They do not need to be plugged in as long as they are familiar to students.
- Make copies of the Energy Conversion Student Worksheet.
- Pre-heat the water to near boiling point to speed up the combustion demo and store in a thermos or other insulated container.
- Set up the combustion demonstration (see Figure 1).
With the Students
- Start the combustion demo by transferring water to flask and lighting the Sterno. Explain the system and that it represents components of a fossil fuel power plant.
- Draw energy flow diagrams starting with various forms of energy. Expect students to be able to help define the energy forms and states.
- We already know about forms of energy in this process (on left of block diagram), now let's define the conversion processes (see added words on right). This model is similar to a coal fired power plant, which would have one more step: the steam would rotate a turbine that has magnets and coils of copper wire. The moving magnetic field causes electrons in the copper to wiggle, thereby creating an electric potential (voltage).
- Who knows what important process is happening between the different forms of energy? State that this conversion is something we use today. Relate it to our use of fossil fuels and the specific combustion process.
- Make sure students understand that energy "losses" occur (energy is converted to an undesired form) as energy is converted from one form to the next.
- Explain that we can model many different energy conversions in household appliances.
- Hand out the worksheets and explain that students will now do the same diagramming for several common appliances.
- Have students look at four different energy conversions and fill in the appropriate information on the worksheet for each conversion.
- Select different objects for each station, depending on what is available at the moment. Examples:
- flashlight (chemical [chemical reaction inside battery] to radiant [light])
- shaking flashlight (mechanical [work to move magnet] to electrical to light [electrical resistance in light bulb])
- light-solar panel-LEGO motor set-up (radiant [light] to electrical to mechanical)
- personal heat packet (chemical to heat [exothermic chemical reaction])
- Genecon generator (mechanical [do work to move magnet] to electrical)
- hairdryer (electrical to heat and mechanical [electrical resistance in wire to create heat, work done by fan to move air])
- glow stick (chemical to radiant [light] [chemical reaction])
- Stress that conversions end with '"usable" and "unusable" forms of energy. Reiterate that energy is never lost.
- Once students have the information for their stations (or all stations) have group each present a station to the rest of the class.
- Make sure that students are able to identify energy forms and states. Require them to show where potential energy loses may occur.
Other Related Information
Susan Powers, Jan DeWaters, and a number of Clarkson and St. Lawrence University students in the K-12 Project Based Learning Partnership Program
© 2013 by Regents of the University of Colorado; original © 2008 Clarkson University
Office of Educational Partnerships, Clarkson University, Potsdam, NY
Last modified: May 6, 2015