IntroductionIn the chemical engineering curriculum, the unit operations laboratory course traditionally serves several key roles in the development of students as professional engineers. The primary goal of the course is to apply chemical engineering theory learned in core courses to the operation of equipment. As part of this process, however, numerous additional skills are often also learned and/or emphasized: experimental design, instrumentation, technical communication, teamwork, and critical thinking, to name a few. [1][2][3] The structure and implementation of the laboratory course will necessarily have a significant impact on the extent to which these skills are developed. In particular, the use of open-ended laboratory activities, as opposed to narrowly defined "recipe"-style activities, seems to be particularly critical for learning and thinking skill development, as shown by several studies in chemical engineering unit operations courses. One previous study suggests that the use of "illposed problems" in unit operations can improve teamwork, critical thinking, and problemsolving, and that active engagement of the students in the problem-solving process can improve retention, decision-making, and self-directed learning. 1 Similarly, another unit operations study discusses how inquiry-oriented activities with troubleshooting, feedback, and discourse with an instructor can also improve critical thinking and goal-setting. 2 Other faculty at the University of Calgary indicate that an experimental design approach with open-ended problems leads to increased student learning and performance when compared with an approach using traditional "recipe-style" laboratory activities. 3 More generally, team-focused project-based learning of this nature has been shown to be beneficial on a broad scale, due to increased student motivation and satisfaction (vs. traditional learning methods) 4-5 as well as due to the enhanced development of skills including data collection and presentation, critical thinking, and independent learning. [5][6][7] Theorists have noted that these beneficial characteristics are likely due to the social nature of the learning that occurs (following Vygotsky's social constructivist theory), in which the task involves active engagement, authentic tasks, application of knowledge in multiple representations, and learning communities. [8][9] Furthermore, project-based learning methods compare favorably with the skills necessary for graduating engineers, as identified by the Accreditation Board for Engineering and Technology (ABET) in outcomes (a)-(k) of Criterion 3. 10 For example, outcome (b) is written as "an ability to design and conduct experiments, as well as to analyze and interpret data", which connects directly to an open-ended laboratory approach. Similarly, outcome (e) requires "an ability to identify, formulate, and solve engineering problems", which coincides directly with providing student teams with "ill-posed problems". From these sources, an open-ended approach would seem favorable fo...