Rhonda,
You are correct that it is difficult because the students are accustomed to getting everything they need to pass the test. It is something that will take some time to change the student expectations. I always start the semester with a discussion of how the class will be facilitated and I tell the students that they will not get everything they need through lectures. It is stressed that anything is fair game for the test, including readings, lectures/discussions, presentations, etc.
Dr. Moody Crews