A visiting colleague and I recently discussed a perennial topic of obsession among some academics: how our departments/universities assign teaching loads.
Some departments (either by choice or by requirement from an external source) have rigid teaching loads that are the same for all faculty. Some departments assign different teaching loads to different faculty as a function of seniority; in recent years, I have seen some departments assign less teaching to assistant professors and more to associate and full professors, but in days of yore, it was the other way around (and may still be in some departments). Some departments assign different teaching loads to different faculty as a function of faculty research activity.
Even if the ratio of research : teaching : service (for example: 45 : 45 : 10) is specified, there is still quite a lot of room for variability in the required or expected teaching load, and there is variability in how courses are counted, as not all courses require the same number of student contact hours.
Both types of system, rigid and flexible, seem to result in resentment about how teaching loads are apportioned.
I've touched on this topic before and am not going to repeat previous posts, but I will give an updated view of my opinion of teaching load distribution methods at universities and colleges that have both research and teaching expectations of faculty.
It was interesting talking to my colleague because his department has recently evolved from a rigid system in which everyone taught the same amount to a more flexible system in which teaching load varies with research activity level. In the past, faculty with grants and grad students taught the same number and level of courses as faculty with no activity other than teaching and service, resulting in some resentment among colleagues. More recently, my colleague's department, in response to both internal and external forces, has moved to a system in which those with active research programs teach 1-2 courses less each year than those who don't have active research programs. This system can also result in resentment depending on how research "activity" is quantified and what the consequences are for low research activity.
If the research-active faculty teach less, the question is whether the research-inactive faculty will teach more or whether new faculty/instructors are hired to teach the courses that were formerly taught by the research active-faculty. I suppose the best answer to this question for each department is related to the expectations of the department/university for the ratio of research : teaching : service .
If there has been a research expectation all along and it was not being met by some faculty, I think is fair to expect them to teach more than faculty who are fulfilling the research expectation. Furthermore, graduate advising is a hybrid teaching/research activity, and should be considered in the research : teaching equation for those who advise grad students.
If the focus is on teaching, however, then it is not fair to add to the work load of those who are already fulfilling their job expectations with their present teaching load.
I have always preferred a flexible system because it gives faculty the option of negotiating the best arrangement of teaching : research : service for any particular academic year. For me, each year is a bit different in terms of number of graduate students, how many are new vs. more senior, whether I will teach a graduate seminar in addition to my undergraduate courses, whether I am writing an unusual number of proposals or need to do an unusual amount of travel (e.g., as a traveling lecturer), and many other factors. I would rather teach more in a non-insane term or year and less in an insane term or year, and a flexible system at least allows this as an option.
It is not always possible to work out an optimal arrangement because of course each individual professor is one of many faculty, each of whom may have complicated professional lives and urgent deadlines. It works out often enough, however, that averaged over time, my research : teaching : service load balances out to what it is supposed to be.
In a typical academic year, the optimal teaching load that best allows me to focus on teaching my classes well; to have sufficient time to advise my grad students, postdocs, and undergrad research students; to do a decent level of research and writing (papers, proposals); to participate in a moderate/high level of department, university, and professional service; and of course to spend some time with my family is: 2 regular undergraduate courses per year + 1 graduate seminar or other specialized course.
Ideally, one or two of those classes will be team-taught, and I will teach 2.5 courses in an academic year.
Some years I teach more than that, some years I teach less than that, but an average of 2.5 courses in a year -- including a mix of big/small and non-majors/majors/grad courses -- allows me to do as well as I can with my various responsibilities.
5 months ago