This project investigated the dimensional accuracy of parts produced using the rapid prototyping method of fused deposition modelling (FDM). Parts with six features common to products were created on a Stratasys FDM2000 out of acrylonitrile butadiene styrene and then measured with a coordinate measurement machine and digital micrometers. An analysis of 12 different dimensions on parts produced using FDM identified that part size, location in the work envelope, and envelope temperature had a significant effect on the dimensional accuracy of FDM.

Students' thinking during an assessment task was monitored by analyzing their explanations of answers to a multiple‐choice question about the equilibrium of bodies under given loads. Based on coding by independent raters, we found that nearly all students explained answers by appealing to force and/or moment summation; they differed principally on whether they applied both force and moment equilibrium and did so consistently. Correlations between answer selection and explanation as found from coding suggested that a reasonable guess as to a student's thinking can be made based on the answer choice alone. By the final exam, some students improved in their ability to consistently apply both principles or at least to apply them when needed. Many other students apparently learned to apply one of the principles consistently, although they came to ignore the other principle, even if they had acknowledged it at the start of the course.

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