Hi Mitessa,
I base my pretests on the specific course. I usually have 2-4 Student Learning Outcomes (SLO's), and maybe 15-25 course objectives. Buried in these are basic principles that I will want the students to have by course end. So I may create 20-25 questions, less if essay style, to assess basic understanding of key objectives. From that, I get a good sense about where students are coming into the course.
Barry Westling