When engineering students struggle with problems, it usually occurs in the problem framing stage when they are trying to identify the relevant principles and concepts and how they are related to each other (e.g., a free body diagram, vapor dome graph, state diagram). We are interested in identifying when students are experiencing difficulty in this problem framing stage so that we can provide meaningful formative assessment in terms of hints that helps them develop better problem solving skills. To identify when students are experiencing difficulty in problem framing, we collected data on student behavior as they solved problems with different levels of complexity. We used Smart pens to record students’ writing/sketching and voice as they used a think-aloud protocol to describe their thought processes. The problem descriptions and information resources were provided within a web-based problem solving environment, ThinkSpace. Our protocol analysis of student cognitive activities during problem solving indicated that there are significant differences in activities between good and poor performing students. This characterization can serve as a basis for identifying students who have having difficulty with problem framing and providing meaningful feedback in order to improve student learning.