This paper presents two studies in the methods of problem-based learning (PBL), where students work in small groups to explore specific problems under the guidance of an instructor. PBL has proven to be highly-effective in engineering education, but there is still room to improve. PBL opponents charge that the unstructured learning environment characteristic of PBL is contrary to cognitive theories on how people learn. Proponents of PBL argue that it is designed to offer just enough structure that students will succeed at learning the material. Studies by Schmidt et al. (2007) suggest that the use of "scaffolds," structures that support the conceptual learning process early-on, but are gradually removed later, can greatly help when students first engage in PBL.

In this paper, the design and use of scaffolds was tested using two scientific studies in an entry-level engineering course. A total of 94 students participated in the research. In the first study, two different worksheets (hard scaffolds) were evaluated; one provided far more structure than the other in conducting the lab procedure and calculating results. After preparing a full lab report, students were given a post-lab examination. The results of this examination indicate that the highly-structured scaffolding was significantly more effective at facilitating the learning outcome. In the second study, the use of lectures and supplementary text (soft scaffolds) was evaluated alongside the improved hard scaffold developed for study one. Students were either given (a) no lecture or supplementary text, (b) lecture/text before lab, or (c) lecture/text following lab. The second study found no significant difference across groups.

When taken together, these results indicate that the process of PBL is effective at teaching students difficult engineering concepts. Specifically, they show that it is the actual process of studying a problem where students learn the most, in contrast to being "fed" information from a lecture or textbook. The results further indicate that students must be provided with a highly-structure scaffold to achieve the highest learning outcome. While further study is needed, the implication for engineering course design is that lectures should be reduced or eliminated in favor of more hands-on problem solving encounters.