I have not yet had a chance to read it in detail, but I spotted this
article in the physics Arxiv and I thought it might interest members of
this list where the topic comes up regularly.
Also, some of the authors cited by the paper are regular contributors.
Single particle models are sufficient for many topics in
introductory physics courses, but become misleading when applied to
situations involving changes in internal energy. This paper argues
that diagrams and graphs enable students to improve their
understanding of these subtle energy problems by providing a
concrete and visual means to track energy storage and transfer. It
also takes the smallest possible step in mathematical complexity -
from one-particle to two-particle models - necessary to achieve
consistency with a sound conceptual approach to energy. It merges
ideas from several previous authors, resulting in an approach to
these issues that is conceptually correct, mathematically rigorous,
and yet simple enough for the introductory student to understand.