These links address strategies for assessing case work.
Evaluating Student Case Work http://sciencecases.lib.buffalo.edu/cs/teaching/assessment/student-case-work.asp
“How do you grade students in classes with case teaching? There are a host of possibilities. Here we deal with only a couple. Let’s start with the toughest.”
Assessing the Case http://serc.carleton.edu/introgeo/icbl/assess.html
“Be sure to assess all that you want students to learn! The way in which students are tested is the most significant factor in how they will approach learning in a course. Be sure to include assessments of the students’ skills in identifying questions, resources, investigative methodologies and argumentation as well as their knowledge of the science concepts.”