The phrase "a teaching load" is correct and commonly used in written English.
It refers to the number of courses or classes that a teacher is responsible for teaching. Example: The new professor was overwhelmed by her heavy teaching load of four classes per semester.
They call it a teaching "load".
Junior professors have a teaching load of between 4 and 8 hours per week, plus administrative and student assessment duties, on top of their research.
Yet, at most prestige universities, any attempt to impose a teaching load that is even half of that would be greeted with outrage.
One small-college scientist I know managed to maintain a productive and serious biochemistry research program for a dozen years despite a teaching load that was recently REDUCED to five courses each year.
Many researchers put in a 40-45 hour week, but only worked weekends/overtime when absolutely necessary (although there were exceptions, especially for younger researchers who also had a teaching load).
Furthermore, with a teaching load of three classes per term, he says that "there is zero time budgeted [for research] during the academic year," so his research often gets shoved into the summer months.
Before taking responsibility for a full teaching load, a beginning teacher needs an extended internship in a classroom, supervised by a trained, empathic mentor.
The chair wants a lot of teaching responsibilities and needs to offer low start-up funds and salary, for example, but the candidate prefers a lab in a good location, a light teaching load, good start-up funds, and comensurable salary.
On top of a booming research lab and a full teaching load, not to mention a growing young family, why would I take on this new venture?
One is to assign some teachers a teaching role, with a heavy teaching load and recognition when they do a good job of teaching; the other is to give teachers a reduced teaching load and expect them to do research or writing.
Come 2014, Dickman says, he'd like to see "not too much prescription, lots of constructive guidance and lots of useable examples, because it's not reasonable to expect a teacher with a full teaching load to completely rewrite all their materials".
