In previous research, we found that the spatial and temporal organization of students' solutions to engineering Statics problems correlates with the correctness of their work. Our technique utilized Livescribe TM Smartpens to capture digital records of students' handwritten solutions. Analysis of the temporal and spatial organization of a solution can, for example, enable an instructor to inexpensively identify students who may be struggling in the course and need extra assistance. This requires, however, that the pen strokes be labeled according to the type of content they represent: free body diagrams, equations, or cross-outs of incorrect work (the ink of the Smartpens cannot be erased). For our initial analyses, we manually labeled the pen strokes, but it is too time consuming to do this for the entire data set. This led to our current work on a technique for automatically determining the content type of the pen stoke in a solution. Our approach correctly classified 93.30% of pen strokes in one experiment. We have used these labeled sketches to detect potentially poor-performing students by comparing the equation drawing time and total length of strokes for each student to the mean from all students.