Viviana,
I use pretests in my courses to establish a baseline on my current students much like what you are doing. In addition, in support of your comments about test taking I like for them to take a test at the beginning of the course that is low stakes, in this case no grade. That way for returning students they can get past the fear of test taking and start to settle back into being students and see that they can in fact be successful in the course.
Gary
Gary Meers, Ed.D.