Some years ago, Ron Bleed of the Maricopa Community Colleges pointed out that a few multi-section large enrollment courses accounted for a surprisingly large share of his colleges' enrollments. It's likely that, at many institutions, these courses (often introductory) are also crucial for whether students become increasingly engaged, or leave the institution.
Large enrollment courses have been at the focus of institutional efforts to improve quality and retention while controlling costs for a long time. Textbooks and lecture halls were early strategies for putting more students in reach of a teacher while, ideally, investing at least some of the savings in assuring that the instructional message was unusually engaging. The Open University in Great Britain developed an even more capital-intensive strategy to enable huge numbers of adult learners across the country, and around the world, to get a quality education at a time when few dollars per student were available to pay the price; their strategy has worked well. In the 1980s and 1990s, Annenberg/CPB invested of millions of dollars into this industrial model (capital investment that could improve quality and accessibility while lowering operating costs): the result included pioneering course materials such as "French in Action" and "The Mechanical Universe." The National Center for Academic Transformation has been a leader in collecting some technology-enabled approaches to redesign. Initiatives such as these have drawn attention because they've had money to solicit proposals and because of their uses of technology.
As I learned while a staff member at Annenberg/CPB, this capital intensive strategy has real potential for improving large enrollment courses, and equally serious limitations. The instructional materials embody the time, place, culture, and teaching approach of their designers, so they are vulnerable to change. Institutions and funders sometimes buy into this strategy because they assume that the high start-up costs can be amortized over 5-10 years of students. Then they're often dismayed to find that expensive upgrades or rebuilding of materials are needed because of changes in the discipline or world events, changes in underlying technology, or simply changes in who's in charge.
Another family of strategies for improving large enrollment courses are less vulnerable to these changes because their initial startup costs are lower than the capital intensive strategies. Some of these are 'cellular' - they increase interaction among very small groups of students (e.g., pairs of students) even in lecture courses of several hundred students. Personal response systems have been quite useful for that purpose. Another, less technical strategy, is to divide a large enrollment course into sections by the educational aims of the students, e.g., dividing a biology course into sections for premeds, prenursing, engineers, teacher ed majors, and so on; each section might use similar materials but their instructors would be prepared to lead discussions and give assignments tailored to the needs of that particular type of student.
Another family of strategies aims to improve the whole large course. For example, some faculty make exceptional use of diagnostic assessment approaches such as Classroom Assessment Techniques (Cross and Angelo). For example, a faculty member might do a diagnostic assessment of students as they enter the course, looking at their needs, goals, or even their personalities. Using the results the faculty member assembles a group of students, and meets with this group every week to discuss the events of the previous week, and plans for the next week. A few of the students in the group are chosen because they are typical of the whole class. The rest are chosen because each of them, in a different way, exemplifies a type of student who is unusual in the larger course. In other words, this small group of students is selected to represent the full diversity of the learners in the large course. The faculty member uses this group to see how the course is working for each of them, and all of them, and to discuss ways of making the course more effective for all of them. The approach, originally developed by Joseph Katz and Mildred Henry of SUNY Stony Brook, is called Paideia.
What families of approaches have you tried, or seen, for improving learning in large-enrollment courses (courses with 100+ students in one or more sections)?