  In an Introductory Physics for Life Science (IPLS) course that leverages
authentic biological examples, student ideas about entropy as "disorder" or
"chaos" come into contact with their ideas about the spontaneous formation of
organized biological structure. It is possible to reconcile the "natural
tendency to disorder" with the organized clustering of macromolecules, but
doing so in a way that will be meaningful to students requires that we take
seriously the ideas about entropy and spontaneity that students bring to IPLS
courses from their prior experiences in biology and chemistry. We draw on case
study interviews to argue that an approach that emphasizes the interplay of
energy and entropy in determining spontaneity (one that involves a central role
for free energy) is one that draws on students' resources from biology and
chemistry in particularly effective ways. We see the positioning of entropic
arguments alongside energetic arguments in the determination of spontaneity as
an important step toward making our life science students' biology, chemistry,
and physics experiences more coherent.
