Exam Design in the Physical Sciences

We are in the deepest, darkest part of our exam schedule and there is a fairly constant stream of students that come to my office with really one question on their mind and they cannot bring themselves to ask it directly so they ask a number of oblique questions that circumnavigate what they really want to ask.

What is on the exam?

In the Physical Sciences there is an expectation of content mastery that typically involves "problem solving" (now there is a term that by itself is a problem). The issue is always how much time do you as a professor allot for students to stare at the ceiling and think during a chemistry exam?

There are a number of aspects of this issue of exam design. Here in a small liberal arts and science college we have the luxury of being able to ask essay questions. This is because the numbers are small enough that we can cope with the marking. In larger universities, even if they don't just resort to multiple choice questions, quite often the questions are choped up into sub-questions so that the marking becomes a series of right / wrong decisions.

At its simplest level the expectation is that the professors will set an exam that the professors themselves can sit down and physically right out the complete, correct solution set in one third of the time allotted. Theoretically, this means that the average student (see below) will be able to write the exam in two thirds of the time allotted and still have one third of the time for thinking / correction / addition.

The real issue comes down to choice. In my exams there is typically choice, especially for the high value questions. Choice is also a luxury of the small liberal arts and science college. The issue with choice however is that there are really two kinds of high value choice questions: 1) the very long death-march question that wrings all the information out of the student that they have learned or 2) the shorter, thinking question that tests what the student understands. If a student decides to answer three death march questions they are going to run out of time and many a tear-stained final exam has ended with the ink trailing off the last page scrawling "ran out of time, exam too long". On the other hand if you have a student that is smarter than the average bear a canny choice of questions can have them out of the exam with a high mark even though they only wrote out one an a half pages of material.

No one ever said that life, or exams, were fair. A University is not a democracy, it is a meritocracy. Perversely, things get easier as you get smarter and harder as you get weaker. Almost Darwinian.