Context: Students are conducting a lab about free falling. They
are required to use a motion detector to draw position vs. time
(s-t),velocity vs. time (v-t), and acceleration vs. time (a-t)
graphs of the free falling of three different objects, a book, a
small basketball, and a box. The motion detector is held above
the objects, facing downward. Moving away from the detector is
recorded as the positive direction.
She wants to check whether the students understand the
relationship between s-t, v-t, and a-t graphs. Below is the
conversation she has with them
SA: What does the position graph tell you?
S: It hit the ground and stopped.
SA: OK. Does the velocity graph match the position graph?
S: Yes, because it increases
SA: OK. Does the acceleration graph match the velocity graph?
S: Yes. If you are increasing at a constant rate, you cannot
a) What conclusion can you draw about the student’s knowledge
based on the information provided above?
b) What may be the student’s difficulties? What support or help
do you think the student needs from the SA?
c) How should the SA respond to the student? Why?