Teaching with cases

Engineering design cases are representations of real engineering situations; they have real data and a real context. They can be used as the basis for a wide variety of teaching situations: lecture presentations, assignments or projects, and/or small group and class discussions.

This flexibility makes it easier to adopt a case to a particular situation, and to gain experience using and discussing cases. Cases are a great way to introduce students to the complexity of real engineering practice, without getting bogged down in details.

For maximum impact on learning, it is important to actively involve students and to facilitate discussion in a way which promotes increasingly higher levels of understanding. This is the basis for the "case method", as practiced in a variety of disciplines including law and business. The figure below is taken from the Ivey School of Business, and schematically illustrates the learning process for an individual student over time.

An important feature of this method is a succession of individual study, small group discussion and class discussion. This provides scaffolding for student learning, and places responsibility on students for their own learning.

1. Group Discussion, and
2. Class Discussion

Members of Waterloo Cases in Design Engineering were asked to provide a guest lecture on the design process for a third year Electrical and Computer Engineering seminar course, ECE 300A. The objective was to reintroduce students to the design process. A case was selected which was relevant for this group, using engineering principles with which they were already familiar, so that emphasis could be placed on the application of those principles in design. The PV Labs Power Supply Design (WCDE-00065) case was chosen. It documents the challenge given to Cameron Burge, a Waterloo co-op student, to design a new power supply for the Eclipse helicopter-mounted image stabilizer system.

The power management system converts the 36V supplied by the helicopter to 5V and 30V, required by the various sub-systems. A preliminary design for this system did not provide sufficient current for the intended applications, and Cameron was asked to design an alternative.

The case study provides an outline of the situation, including a system block diagram for the various sub-systems and general specifications for the required power supply. Students in the ECE300A class were asked to read the case study one week before the lecture, and to individually answer some general questions. The objective of this approach is to ensure that the students are familiar with the situation prior to the class discussion, and get them thinking about how they would approach the problem, to prime them for a discussion of the design process. They were asked to assume they were the co-op student asked to do this design, and to identify 4 things that they would need to know before they proceeded. They were told that this list would contribute to the list of specifications for the final design.

The lecture began with a brief overview of the case, including a video demonstrating the Eclipse in action. To frame the discussion of the design process, students were provided with an overview schematic which emphasized the purpose: to move effectively from an engineering challenge to an appropriate solution. Other features of a design process are that it integrates domain knowledge with design process knowledge, and must accommodate constraints, both on the design process itself and the solution.

To further frame the discussion, a specific design process was presented: the stage-gate process. It is emphasized that this is only one of many potential processes. Important features are that it has several stages wherein the problem is more clearly defined, and the solution is developed and successively refined. The gates are used between stages to obtain stakeholder feedback and approval to continue to the next stage. Finally, the importance of appropriate documentation is stressed.

In this lecture, the early stages of the design process are emphasized to highlight the importance of thoroughly understanding the problem, and to provide students an opportunity to exercise their judgement by defining this particular problem – identifying important requirements and prioritizing them. Such decisions must be made to fit the case discussion into the time available.

Students were asked to build on their pre-work assignment and work in groups in class for 3-5 minutes to identify as many engineering specifications as possible. They were introduced to a categorization system for specifications (requirements, constraints and criteria), and during the class discussion the complete list of specifications was developed and their classification was discussed. The lecture continued with the presentation of Cameron`s list of specifications. These are contained in separate modules of the case study which are not released to students, but made available to instructors to help guide discussion.

Students were then asked to suggest possible power supply configurations which could be used to address this need. Cameron`s choices were then presented and his selection process highlighted. His preliminary design (circuit configuration and key components) and then detail design (specification of all components) were presented. This included the results of his simulation to verify the performance of the chosen design.

Note that this case was used in this course over one lecture period to illustrate the design process. The same case could be used in a number of other courses to achieve different objectives. For example, it could be used in an introductory circuit course by having the students analyze the selected circuit, or in a more advanced course by having the students actually design the circuit.