Alaska Science Key Element A8c A student who meets the content standard should understand the scientific principles and models that state that whenever there is a transformation of energy, some energy is spent in ways that make it unavailable for use (Energy Transformations).
 Performance Standard Level 3, Ages 11–14 Students examine energy transfers and identify energy that is useful vs. energy that is unavailable. Sample Assessment Ideas Students identify energy transformations in the community (school and home especially); design a way to measure the efficiency of an energy transfer (e.g. electricity to light); confirm what happens to the “lost” energy. Students research and report on the efficiency of light bulbs, refrigerators, and other household or community appliances; contact local appliance stores for this information or write to the manufacturer; describe what happens to the remaining energy (e.g. if a light bulb is 40% efficient, what happens to the other 60%?) Expanded Sample Assessment Idea Students carry out a standard calorimetry experiment to compare energy losses in different calorimeters.
 Materials hot plate metal blocks with holes for thermometer tongs calorimeters (styrofoam cup and lid with hole for thermometer) Procedure Students will: Measure the volume of water required to fill calorimeter half-full of water; heat this amount of water to near boiling Weigh the metal block; insert thermometer and measure temperature of metal block; record measurements Determine the “calorimeter constant” (i.e. quickly add a known volume of water at a known temperature to the calorimeter; measure the immediate drop in temperature; calculate the heat needed to heat the calorimeter from room temperature to the temperature just measured. Place the metal block at known temperature into the hot water in the calorimeter; measure the temperature change over a few minutes; record data Graph data; extrapolate back to “zero time” to get specific change in temperature Graph the calorimeter’s heat loss over time Compare results with other students in class. Reflection and Revision What are the efficiencies (heat retained or total heat loss) for the different calorimeters? Where happens to the heat energy that is “lost” from the calorimeter? How could you change the design to improve the efficiency of your calorimeter? How can this information about efficiency and heat loss be used in an application in the community? Levels of Performance Stage 4 Student work is complete and shows clear evidence of ability to conduct a reproducible experiment to measure heat loss. Data and observations are recorded in detail, graphs accurately represent the data, and the student describes an appropriate method to reduce the heat loss of the calorimeter. Community applications are discussed in detail and show extensive evidence of the transfer of knowledge. Stage 3 Student work is mostly complete and shows evidence of ability to conduct a reproducible experiment to measure heat loss. Data and observations are recorded, graphs are drawn to represent the data, and the student describes a method to reduce the heat loss of the calorimeter. An example of a community application is discussed and shows evidence of transfer of knowledge. Stage 2 Student work may be incomplete and shows limited evidence of ability to conduct a reproducible experiment or measure heat loss. Data and observations are recorded but errors are made. Student may not include suggestion for improving the measurements. Student may identify a community application but the explanation lacks detail and show limited transfer of knowledge. Stage 1 Student work is mostly incomplete and shows misconceptions regarding experimental design and heat loss. Data and observations are incomplete or incorrectly recorded. Community applications, if present are incorrect and show evidence of misconceptions.
 Standards Cross-References ( Alaska Department of Education & Early Development Standards) National Science Education Standards 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. (Page 155) The sun is a major source of energy for changes on the Earth’s surface. The sun loses energy by emitting light. A tiny fraction of that light reaches the Earth, transferring energy from the sun to the Earth. The sun’s energy arrives as light with a range of wavelengths, consisting of visible light, infrared, and ultraviolet radiation. (Page 155) Benchmarks Most of what goes on in the universe—from exploding stars and biological growth to the operation of machines and the motion of people—involves some form of energy being transformed into another. Energy in the form of heat is almost always one of the products of an energy transformation. (Page 85) Heat can be transferred through materials by the collisions of atoms or across space by radiation. If the material is fluid currents will be set up in it that aid the transfer of heat. (Page 85)