DASI-P

What important physics idea is this question targeting?

This question addresses whether or not students can apply the conservation of energy in situations with non-contact forces to make a claim about changes in potential energy. In particular, if they can use ideas about forces to determine acceleration, and then changes in kinetic energy and therefore potential energy. (C)
This question addresses whether or nto students can use forces of magnetism, electricity and gravity to determine when a force is strongest and therefore the acceleration is greatest. They can use this information to determine if the potential energy is increasing in a system. (I)
This question targets students' abilities to use the law of conservation of energy in a range of different real world scenarios. (V)

Student A's response:

Which answer best describes what student A's response indicates about their physics understanding?

This student has a strong intuition that potential energy increases when an object is being "forced to move." However, they don't distinguish between whether the force is coming from an outside source (the hand) or an internal force (the repulsion between two magnets). (C) -- [*I love this response and it's really on to something and I don't want teachers to miss it!]
The student response suggests that they do not understand the conservation of energy; they think that energy can be created by applying a force. (I)
The student has a range of misconceptions that need to be addressed. (V)

Which of the following options would best support Student A in being able to correctly respond to this question?

I would give them a graphic organizer to help them see the patterns between forces, displacement, and changes in kinetic energy for each scenario. We could then determine the changes in potential energy from that using the conservation of energy.
I would start by giving them an overview of the conservation of energy and then ask them to consider whether the object is getting closer to or farther from the source of energy in each scenario. (I)
I would have students create diagrams of energy flow for each scenario to compare to one another. (V)

If the magnets are going away from each other they will go to where there is no force so they are losing energy as they go. The balloon is getting close to the sweater where it will stick to it with a lot of energy. The ball is so close to the earth that it doesn't really change the gravitational force, so the energy doesn't change. And the cart has no force so it has no potential energy.

Which answer best describes what student B's response indicates about their physics understanding?

This student considers the strength of a force to be an indicator of the amount of potential energy.
This student has strong ideas about forces and energy but they are oversimplifying things, like that the force of gravity is not changing (it does slightly) or that the force from a magnet is zero (it is small but not zero).
The student has not explained their ideas clearly enough with evidence and reasoning.

Which of the following options would best support Student B in being able to correctly respond to this question?

I would give them springs to compress and stretch as a model for thinking about how forces can store potential energy, and a graphic organizer to track when the force is strongest, when the force is weakest, and where the kinetic energy changes the most. We could then determine the changes in potential energy from that using the conservation of energy and relate this pback to how attraction and repulsion store energy.
I would reiterate that even small changes in force can tell us something about how the potential energy in a system has changed, and to repeat this question keeping that in mind. We would then discuss as a class to resolve any misconceptions.
I would give them sentence stems to work from that help connect forces, kinetic energy and potential energy, such as "When a force ______, the kinetic energy ____ and, because of conservation of momentum, the potential energy _______."