How did we embody the rules of energy during Energy Theater?
Energy "Rules":
The total amount of energy remains the same (energy is not created or destroyed)
Energy is contained in objects
Energy can move from one object to another [Transfer]
Energy is of different forms and can change from one form to another [Transformation]
Patterns of Energy
Dissipation
Motion Energy transforms into Thermal Energy
If it didn't disappear, where did the energy go?
Thermal energy transfers to the environment (air, the ground, oceans) and "spreads out" but does not disappear.
How do we really know that energy is not created or destroyed? Do we need to take this on faith or is there something that proves this is correct?
Some "rules" we do, to some degree, take on faith or are asked to believe.
We can look to previous scientific experiments to seem to be able to lead to this "rule": we can always see where the energy comes from and goes using evidence.
Logical argument: would it make sense for energy to just disappear?
What happens to thermal energy?
Does it go back into chemical?
Does it go into space? Once there, where does it go?
Energy in Biological Systems
Rules:
Chemical energy is stored in a substance (the molecules) of an object, not the object as a whole.
Logs, can of gas, marshmallow: can be treated as objects (like rubbing a marshmallow on the table), but in this discussion, we want to think of the smallest part of the object that is still considered the object. "The smallest piece of marshmallow."
Chemical energy transfers happen when molecules rearrange (when substances change) - and vice versa. If you see a substance change, there must have been an energy transfer.
When the smallest piece of that material is changing, there is a chemical energy transformation.
The matter (atoms) of the molecules does not transform into energy, and energy does not transform into the material. In all chemical reactions, rearrangements of molecules happen, but the same amount of material is present before the transformation as there is after the transformation.
Molecules of the marshmallow do not turn into energy. The arrangement of the marshmallow atoms have changed (which means it is no longer marshmallow) and energy has transfered.
Often, each time chemical energy is transferred in living systems, some of it is concurrently transformed into thermal energy.
Chemical to kinetic and thermal (pushing a box: chemical energy of your body into movement of the box and your muscles heat up).
Chemical to chemical and thermal (molecules/chemical in your body changing into other chemicals and thermal energy)
Our living systems are not 100% efficient.
End goal: Food chain: Grass t0 cricket to sparrow. What is going on with energy? How is energy involved?
First scenario for Energy Theater: A person eating pasta and then running a marathon.
Second scenario: A person eats too much pasta, gains weight, and then a week later runs a marathon.
Energy Diagrams for our scenarios: Diversity of ways to draw our energy diagrams? Good or bad? Conventions? There is a convention for doing energy diagrams. It is not the only way, it is not required, but it is a model that is often used and might be helpful in certain contexts or situations. Your own diagrams might be able to tell more or different information from the conventional model diagram. (Here is a sample energy transfer diagram.) The basic diagram shown in the link does not show a full diagram, there could be multiple answers to different object. (Here is a "real life" example of a possible complex energy transfer diagram for energy usage in the US [Side note: what does "lost energy" mean in that diagram?] (and here is the corresponding article)).
In our second scenario, we know that chemical energy of the pasta was turned into chemical energy of a fat molecule. Firstly: Should a distinction be made between chemical energy of the pasta and "stored" chemical energy of the fat? In our understanding of chemical, there is no difference. The energy may have changed (because the molecules changed), but both are chemical energies. Secondly, what happens to the fat when the chemical energy of the fat is transformed into kinetic and thermal energy (as you run)? Refer back to our rules. #2 says that molecules rearrange if there is a chemical energy transfer, the atoms that make up the matter are still there, but they are a new, different substance now. That fat has turned into carbon dioxide and water (both of which also have chemical energy) along with thermal energy.
Two more scenarios: (1) Grass grows and is eaten by a cricket. (2) Grass clipping in a compost pile decompose, the compost pile becomes warm.
Energy story for scenario 1: Light energy to the chemical energy of the grass (via photosynthesis) to chemical energy (and thermal energy) of the cricket (thermal and kinetic energies should also be included in this scenario along with the environment). Notes on photosynthesis: ALL of the energy of the plant comes from the light, but the substance comes from the carbon dioxide and water. When the carbon dioxide and water are combined (a rearrangement, see rule 2) a new substance is formed that has MORE chemical energy than the carbon dioxide and water had alone. The ENERGY came from the light, the MATERIAL came from the carbon dioxide and water. Yes, we need other things to live/grow (nutrients), but they are not part of the energy story.
Energy story for scenario 2: Chemical energy of the grass to chemical energy and thermal energy of the decomposer (and the air [note: a LARGE portion of the original chemical energy is released to the air at this point]) to kinetic energy of the decomposer to thermal energy of the air. The mechanism is through decomposers. Rule #2 still applies, the material is changing its structure when chemical energy is converted into thermal energy.
Our end goal should be easy to put together now. We started with light energy from the sun and everything ended up and thermal energy in the environment. From an earlier discussion, we want to know what is the end fate of the energy? Does it go back into chemical energy? No, from what we have seen, there is no way for it to cycle back into chemical energy. It must have another fate: outer space. The thermal energy in the atmosphere is able to turn back into light energy and radiate (through infrared back into space).
Note on the difference between water cycle and energy. With the water cycle, water is constant used over and over again, the matter is always the same. With energy, we get it all from the sun, we do things with it that end up as thermal energy which is then radiated as light energy back into space. Energy is NOT used again like a cycle, it all comes from the sun and once we use it, it is laves the earth (it still exists, see Energy Rule #1, it is just unusable to us).
How do we bring what we have been learning into our own classrooms?
Being careful not to over simply because that could lead to misconceptions.
What do we want the kids to master? Are the state standards enough? Should we be pushing beyond the state standards since they don't have much there?
Looking for guided inquiry and not just discovery for anything, but that it is focused and it is okay to give answers sometimes. Being given individual time as well to work through the concepts.
Using energy theater as a way to help teach energy transfer diagrams.
Today's Reflection:
What instructional strategies have supported your learning? What have you seen modeled (both from instructors and group members)?
Homework: Reading from the 10 Minute Ecologist: "Who Eats Whom?"