Hi Christine:
I don't think pretesting has to be done in every class or even all the time.
Where it's helpful is leraning at what degree of knowledge or performance your students are so that you can tweak your curriculum in order to put the emphasis where it'll do the most good.
Students usually don't mind "a test" if they know it won't count toward's a grade (unless you decide to make it so). I wouldn't recommend making a pretest a graded activity.
Regards, Barry
