DASI-P - Wave Properties Selected Response

Add information to the axes on the images!! --
Below are two images of sound waves traveling in air. The y-axis indicates the change in air pressure, while the x-axis represents distance.
Then only ask the first question: "which one is traveling faster" (and delete student responses to the second question)

What important physics idea is this question targeting?

This task assesses whether students can draw relationships between the shape of a wave and how quickly it can move through a medium. Specifically, if they recognize the direct relationship between speed and wavelength, the inverse relationship between frequency and wavelength, and that speed doesn't depend on amplitude. (I)
Students can have trouble interpreting what a drawing of a wave represents and how to use that to infer characteristics of the wave. This task reveals whether students can determine frequency and speed from a graphical representation of pressure/distance for a given medium. C)
This task assesses students' ability to compare two waves by using only graphical information. (V)

Student A's response:

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

It sounds like the student is thinking that the waveform represents a path along which the wave travels over time, instead of a snapshot of a wave. (C)
The student is able to infer that the wave with the higher frequency will cover more distance for a given period of time, and is therefore faster. (I)
The student is able to draw conclusions about speed and frequency from the given graph and understands key vocabulary. (V)

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

I would hand out a picture of a spring with a compression wave traveling through it, and have students create a graph showing (roughly) how displaced each coil is along the spring. The resulting graph should look like a sine wave and we could use that to discuss the difference between how the medium itself moves and what the graph of the wave looks like. We could then revisit these questions. (C)
I would encourage the student to use our equation for waves (v = lambda-f) to check their claim that the shorter wavelength would have the higher speed, and write their response in a standard claim-evidence-reasoning structure. (I)
I would have the students do a lab activity with springs to test their ideas. (V)

Student B's response:

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

Student B's reasoning is consistent with thinking that waves A & B have the same frequency, but the wavelength and speed can vary, suggesting that they understand the relationship between speed and frequency but have made incorrect assumptions about what is constant in this scenario. (C)
Student B's reasoning suggests that they are having difficulties with scientific vocabulary, and think of "fewer waves" as "lower wavelength." This causes them to draw the wrong inference. (I)
The student is not able to apply the equation for wave speed correctly. (V)

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

I would hand out a slinky with a point on it marked (maybe with yarn) to a pair of students and ask them to stand a set distance apart and try to reproduce a similar pattern: a shorter-wavelength and slightly larger amplitude waves, and then longer-wavelength but shorter amplitude waves. We could then discuss why a faster frequency creates smaller wavelength before relating it back to this representation and the constant speed of sound.
I would ask them to annotate these graphs indicating what is the wavelength and amplitude, and then indicate how they used those to find the frequency. We could then compare with others and guide the class to the correct understanding.
I would have them revisit our lecture notes on waves and underline any relevant terminology and equations to then ensure they have applied those correctly.