Might be useful to take advantage of this for teaching/explaining:
"People also seem to use misleading heuristics to assess how well they understand a system. Most notably, if they can see or easily visualize several components of a system, they are more convinced they know how it works. Thus, the more easily visible are parts in a system, relative to hidden ones, the stronger the IOED (Rozenblit & Keil 2002). Visual influences of this sort may be related to the appeal of visual “mental animations” in constructing and evaluating explanations of devices (Hegarty 1992)."
From Keil, 2006; Explanation and Understanding