I respectfully disagree with the argument made by Scott Milam in his response to Erica Adam-Posthuma's post about energy. I believe that metaphors are very powerful tools for helping us make sense of the world. Consider for a moment how we try to make sense of "light". We call it a particle or a wave when it is actually neither. Nonetheless, these metaphors are useful for helping understand and predict its behavior in different situations. The same reasoning applies to energy. While we no longer believe that energy is "substantial" (like caloric), the use of the substance metaphor helps us understand important aspects of energy.
Energy is an attribute of a physical system. A sample of particles of a substance at 100°C has more of this "stuff" than do the same particles at 50°C. Liquid water at 0°C has more of this "stuff" than does water in the solid state at the same temperature. Students find that this makes sense.
The transfer of energy between system and surroundings is accompanied by changes in both - we call energy an agent of change.
Energy also appears to be conserved during transfers within a system or between system and surroundings. If we are careful in our accounting, the amount of this "stuff" does not change.
These are all properties/behaviors of a substance; hence, we describe energy as substance-like.
Since I have adopted the treatment of energy promoted by Modeling Instruction I have found that my students (and the teachers I have worked with) have felt much more comfortable with the role energy plays in change. They have a set of tools (which Erica has outlined nicely) for describing ways that a system can store energy and how energy can be transferred between system and surroundings. This deep conceptual understanding also helps them with their quantitative treatment of energy. I think the use of this metaphor is much more satisfying than the approach that energy is simply "invented" to help us with calculations.
Published
Comment on A Modeling Approach to Energy Storage and Transfer
I respectfully disagree with the argument made by Scott Milam in his response to Erica Adam-Posthuma's post about energy. I believe that metaphors are very powerful tools for helping us make sense of the world. Consider for a moment how we try to make sense of "light". We call it a particle or a wave when it is actually neither. Nonetheless, these metaphors are useful for helping understand and predict its behavior in different situations. The same reasoning applies to energy. While we no longer believe that energy is "substantial" (like caloric), the use of the substance metaphor helps us understand important aspects of energy.
These are all properties/behaviors of a substance; hence, we describe energy as substance-like.
Since I have adopted the treatment of energy promoted by Modeling Instruction I have found that my students (and the teachers I have worked with) have felt much more comfortable with the role energy plays in change. They have a set of tools (which Erica has outlined nicely) for describing ways that a system can store energy and how energy can be transferred between system and surroundings. This deep conceptual understanding also helps them with their quantitative treatment of energy. I think the use of this metaphor is much more satisfying than the approach that energy is simply "invented" to help us with calculations.