  The ability to flexibly transform between different representations (e.g.,
from mathematical to graphical representations) of the same concept is a
hallmark of expertise. Prior research suggests that many introductory physics
students show lack of representational consistency, e.g., they may construct
two representations of the same concept in the same situation that are
inconsistent with one another. In this case study, we asked students to
construct two representations for the electric field for a situation involving
Gauss's law with spherical symmetry (charge conducting sphere surrounded by
charged conducting spherical shell). Prior research also suggests that this
type of problem results in many students constructing representations that are
not consistent with one another. Here we present findings from individual
interviews with three students about this problem which suggest that students'
lack of representational consistency may be partly attributed to the type of
knowledge that the graphical and mathematical representations trigger. In the
epistemic games framework terminology, the two representations students are
asked to construct (mathematical vs. graphical) in the problem may contribute
to their lack of representational consistency.
