When moving from the qualitative particulate view(e.g., which figure is most consistent with a gas?) to a more quantitative view (e.g.,associating figures with particular values of T and P),one must be especially cognizant ofthe role that the motion ofthe particles plays.In fact,Sanger et al.(12) have identified the lack of motion in the figures as one potential threat to the question's validity and examined the role that animation of the particles in these assessment questions played in student learning outcomes.