Many of us assess students multiple times during a course — whether for the purposes of formative or summative assessment. Few of us, I think, do this properly, because we don’t establish a baseline or benchmark of students’ knowledge with a pre-test when the course begins. If no baseline is established, there is no sound method of determining improvement.
In this country, probably the most frequently used pre-test for undergraduates taking political science courses is the U.S. naturalization (citizenship) test, but the use of even this very basic instrument is up to the individual instructor. There is definitely no widely-employed test of “essential” knowledge in political science. We haven’t even clearly defined what that common body of disciplinary knowledge might be, much less operationalized it in the form of a widely-adopted pre- and post-test instrument. The situation gets even worse when one teaches courses in sub-fields like comparative politics. Our definitions of what we consider fundamental to these topics can be very different, and no ivory tower academic likes to be told what to do in the classroom.
I’m definitely guilty of contributing to the problem; I have never systematically pre-tested in any of my courses. I’m making a summer resolution to change that for the fall semester. At minimum, creating pre- and post-tests should help me clarify in my own mind what particular learning outcomes I want my students to achieve in any given course.
You make a very important point: political science has no consensus about what our students can be expected to know upon completion of a degree or a particular unit of instruction. In this respect, we are lagging behind other disciplines. In the natural sciences, there are “concept inventories” that measure knowledge about the key aspects of crucial concepts like “force” etc. I see no reason why we couldn’t strive for something similar.