I am wondering about what incentives professors have to teach a large class (vs. a small class). To put it differently, when a professor is assigned to a class, what motivates him/her to attract students to his class? I am looking for external motivations, not personal ones, such as willingness to share the class materials to as many people as possible.

I am mostly interested in the United States, but curious about other academic systems as well (at Mars University there seems to be none).

  • It might help if you try to give a better idea of what you mean by "small" and "large". In some situations, 30 students would be considered a large class; in others, it might be considered small. If I only had 9 students in my class, I might try to actively get it to grow. But if I had 30, I would consider that "large enough" and cease my recruitment efforts.
    – J.R.
    Aug 5 '15 at 22:13
  • 1
    As Peadar's answer points out, it depends on a lot of factors. I teach physics and math at a community college in California. Class sizes are set through a bureaucratic process that includes both faculty and administrators, with faculty -- and, indirectly, our union -- pushing for smaller sizes and administrators pushing for larger ones. Justifications for small class sizes include the fact that there's a lab or that the class is writing-intensive. If you teach a section that's bigger than the set size, the contract says it counts as teaching some multiple of the normal units.
    – user1482
    Aug 5 '15 at 23:42
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    Continued employment in an anti-intellectual country. :|
    – Chris
    Aug 6 '15 at 6:33
  • Are you asking about why would an instructor choose/agree to teach a set large lecture classes like Calc I, or why a professor might actively recruit students to enlarge the class (e.g., for a topics course)?
    – Kimball
    Aug 6 '15 at 7:29

At my institution in my department, I think there are two major external incentives:

  1. The number of teaching assistants is a function of the number of students in the class. Critically, below some threshold size n, a professor will not receive any teaching assistants.

  2. Offering the class in the future may depend on enrollment in the present.

In some other departments,

  1. Professors who teach classes with more than N students get double credit for that class, so if they typically teach 4 courses a year, they could instead teach 2 small courses and one large course with >N students.
  • What's the typical size of N?
    – Bill Barth
    Aug 5 '15 at 17:12
  • 4
    Over 100 at my school. I'm sure it varies.
    – ewormuth
    Aug 5 '15 at 17:32
  • Indeed. Where I was a graduate student, N was about 30-35.
    – Jeff
    Aug 5 '15 at 17:37
  • 1
    @Jeff are you saying n or N? To get double credit for 30 students seems crazy.
    – StrongBad
    Aug 5 '15 at 18:02
  • 7
    @StrongBad Believe it or not, I'm saying N. The normal class size was 30 students, and the cap could be increased to 35 at the instructor's discretion, but due to classroom sizes, that was it. The only way you could have more students would be to teach a "double section" of 60-65 students, and this would necessarily take place in a much larger classroom.
    – Jeff
    Aug 5 '15 at 18:07

One other incentive that I have not yet seen mentioned, and which might or might not count as "external," is that teaching a class is often the earliest stage of various recruitment pipelines. If more students are interested in a class on X, then:

  • if the class is early enough in the sequence, it may attract more students to the department (most relevant in those colleges where majors are chosen after the first year or are easy to change).
  • students already in the department will be more likely to take the higher level follow-on classes regarding X, as opposed to their other options.
  • strong students are likely to become interested in research related to X, and may become undergraduate researchers or apply to become graduate students.
  • growing student demand for area X may affect what types of faculty candidates a department is interested in recruiting.

All of these are relatively long-term and indirect, but can be a significant motivator for instructors who are strong teachers and strategic thinkers.

  • 3
    +1 for recruiting undergraduate researchers. Getting top students to write their thesis at your department is definitely a motivation, especially if it is custom to keep your best undergraduates as graduate students. Aug 5 '15 at 18:46
  • Yes, but being the one very bright student in a 100 class is not much of a incentive for that desirable student...
    – vonbrand
    Aug 5 '15 at 19:46
  • Start before recruiting: is there a better teacher at your department for the material you want people to get before they can work for you?
    – Raphael
    Aug 6 '15 at 8:49

Departments I am familiar with have a minimum size that a course has to be to run. If you want to continue teaching the course, it is helpful to grow the class in a way to consistently exceed the minimum. This usually means you want to be attracting at least 10-20 students. Once you hit 30-40 students you can often get a TA to help with office hours and grading. With 100+ students in an upper level class, departments I have been in either let you teach two sections or reduced other teaching requirements. I have never heard of upper level classes getting much bigger than 100 students.

For intro classes, the incentive for growing seems reduced as the numbers are already large, and generally there are multiple sections.

  • Somewhat related: classes also might have a maximum size. For example, if a methods course I teach attracts more than 28 students, I get two classes of 14 students instead of one of 28 (and the double amount of teaching hours). As I obviously only have to prepare the course once, it is very attractive for me teaching the same course twice. Example from the Netherlands.
    – damian
    Sep 24 '15 at 12:33

I would suggest that the type of institution plays a large part in the level of effort a faculty member does or doesn't put in to attracting students. In an R-1 or similar you may want to grow possible graduate students or undergraduate research assistants. A teaching-focused college won't have this requirement, for example.

There's also the question of supports. In my own college, we're almost entirely focused on teaching, which means we don't have TAs for the most part. Growing a lab focused class beyond about 24 would make it unmanageable since the lecturer is on their own, and damage the learning experience of all the students. However, a class that was mostly lecture-based could probably stretch a bit more. My last college was an R-1-type institution where supervising a lab of 70 was fairly straightforward.

More important is the matter of student motivation. A small motivated class that has a good group work ethic almost teaches itself, whereas a class where half of the students don't really want to be there is a totally different undertaking.


A fundamental assumption of your question is that the professor has been incentivized. In many cases, there is no incentive, beyond "The Chair told you you're teaching X" and X is inherently a large class. In my experience, this is how most of the folks I know who ended up teaching large classes got them.

Beyond that, another reason might be class dynamics. Perhaps you prefer to teach via a "Lecture and Test" style, which is harder to do with a smaller, more intimate class. Or you might need a certain number of students for group work, discussion groups, etc. to be viable approaches.

As others have mentioned, classes can be viewed as Step 1 in recruiting grad students, and thus you might want a larger pool to draw from.

Finally, teaching a large class potentially has a larger impact on the way the department works than a smaller class. Teaching your "vision" in one of the larger core methodology classes in a Department may impact the feel of that department, outlook of students, etc. over a small, specialized seminar.

  • No incentive is a valid answer as well, my question didn't exclude it. Sep 24 '15 at 22:39
  • I guess the incentive in this case is "keeping your job". Sep 24 '15 at 23:49
  • @NateEldredge Or "not wanting to restart my job search again..."
    – Fomite
    Sep 25 '15 at 0:08

As budgets shrink, pressure from administration may also provide incentive for larger classes. Some higher-ed administrations are starting to measure various sorts of "productivity," and $-per-student is certainly on the table.

This raises the spectre of classes that instructors love to teach being cancelled for low enrollment (and thus high $-per-student) unless balanced by higher-enrollment courses.


To supplement other answers and comments... :

In some cases, an instructor can get negative incentives to attract students, the supposed rationale being that this takes students away from other courses in the same department, pushing them to sub-acceptable enrollments. I myself experienced this some years ago having developed a then-new-ish crypto course and a then-new-ish error-correcting codes course within a (pardon me, but, somewhat stodgy) math dept. The traditional-stodginess leads to courses whose names and catalog descriptions were/are incomprehensible (and certainly not attractive) until possibly after one has taken the course... So, in that context, it is easy [sic] to develop a course that will attract students... but/and this might be (was) construed as extremely hostile to other courses/faculty in the environment.

On another occasion, when it was proposed to increase the size of lower-division math classes (mostly calculus...), when I asked whether that wasn't moving in the opposite direction of more effective teaching, the answer was that things were already so bad in that regard that the marginal worsening would be less than the gain in freed-up person-hours of instructors. Sure, the kids are pretty negligent students, but, still, ... ?!?!

So, in lower-division courses in math, the motivation for larger class sizes is "efficiency". And instructors with 200 students have virtually no responsibility for the individual success/failure, ... even the TAs usually have 60-80 kids... For upper-division, it takes a certain number to "run" the course. Beyond that, it is actually unwise and undesirable to rope-in more people if they're not really qualified or interested, since it drags things down... and in some cases one can be accused of sabotage of colleagues' courses!

For graduate courses (in math), again there's a minimum usually required, so one wants to offer something that appeals to more than 1 or 2 people. Beyond that, again, there is some push-back that one might be taking away from colleagues...

And, I note, in all cases I myself have been accused by colleagues of "pandering" to students (at all levels) by trying to engage/entertain/edify them... as though being boring were a fundamental virtue in the teaching of mathematics. And, also, the idea that exams contain "surprises", so that no one knows what to study, apart from "everything", etc. That really doesn't seem a productive pedagogical strategy, since the kids cannot effectively study/learn/assimilate "everything".

(The devices that one might use to maintain close contact ... often unwanted!... with large student populations are not subtle, but require some technological savvy. My experience is that the system-gamers were amazed-and-incensed that anyone would manage to prevent... in a large-population situation where they'd hoped for quasi-anonymity. Poor kids...)

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