DASI-P - Ball Toss Selected Response

What important physics idea is this question targeting?

This question targets whether or not students can describe how a force changes over time and the impact of that changing force on the speed and acceleration of an object. (I)
This question is designed to assess whether students can distinguish between the concepts of net force, velocity, and acceleration — and understand that these don’t always peak at the same time.(C)
This task examines if students can use Newton’s Laws to correctly identify the forces and acceleration and velocity of a ball. (V)

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

The student is mostly correct: they are clearly reasoning about the air resistance acting on the ball, which shows they’re considering real-world physics in this problem. And the student’s answer shows they know that “acceleration is when speed changes. " They need help with language around how to describe gravity on the ball. (I)
The student treats force as something the ball receives from the hand or from gravity over time. Because of that, they don't recognize that the force of gravity on the ball is the same throughout the toss, while the force of the hand only acts when the hand was touching it. They do seem to understand that acceleration and change in speed are correlated. (C)
The response reflects early reasoning about dynamic systems and a desire to make sense of real-world scenarios through force analysis. (V)

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

I’d have the students do a lab with a ball toss with a motion sensor or video analysis. We’d look at graphs of velocity vs. time and acceleration vs. time, and discuss why acceleration is constant even when speed changes. This would help them separate force, velocity, and acceleration.” (C)
I’d have them create free-body diagrams and clearly label all the forces that are acting. I would encourage them include air resistance in creating free-body diagrams since that adds complexity and makes it more realistic. That way they can see how the total force changes over time as they predicted. (I)
I’d assign a group task where students rank each moment by speed, force, and acceleration and explain their thinking to one another. (V)

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

They’re thinking about how energy builds and decreases and relating that to forces and acceleration, which shows they’re ready to move beyond Newton’s Laws and into energy modeling. (I)
The student is comparing the acceleration it took to get the ball started from rest, and comparing it to the accerlation from the top of the toss to conclude that the intial force is larger. It is not clear if they think that strong force is acting after the hand lets go, or if gravity only acts as it falls. (C)
This student is reasoning across multiple domains (force, motion, energy), which is a strong sign of conceptual integration. (V)

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

I would have students look at a range of scenarios in which speed changes slowly or quickly, and then use those to determine when the force on an object was the greatest. We would then be ready to link this to change in kinetic energy and to work. (I)
I’d have the student annotate a speed v. time graph with notes on speed, force, and acceleration at various moments — then compare those to a force diagram for the same moments. This helps distinguish between change in velocity and force that intiially caused the velocity, and shows that acceleration can be constant even when velocity changes gradually. (C)
I’d ask students to write a paragraph explaining what’s happening to the ball using only the physics terms of force, motion and acceleration, then have them check their responses with our definitions for those terms before comparing answers in small groups. (V)