This is a question that comes up frequently in faculty development circles. Teachers who want to spend more time in class with active learning are understandably reluctant because they know that students won't come to class prepared for discussion, problem-solving, group work, etc.
Recently Faculty Focus posted two articles that provide some solutions both for getting students to read and for encouraging comprehension.
Maryellen Weimer reports on a study by Terry Tomasek that includes prompts to encourage critical thinking over the reading. Whether you want your students to be able to identify problems or issues in the reading, make connections, interpret evidence, challenge assumption, or apply what they read, there are specific prompts to foster these different levels of thinking. Tomasek decides first what level of thinking she wants her students to engage in, and then she assigns one prompt at the time the reading assignment is announced; students respond in one or two paragraphs prior to coming to class using Blackboard. These pre-class postings then provide fodder for in-class discussions.
In the post "Two Strategies for Getting Students to Do the Reading," Weimer reports on a study published in the International Journal of Teaching and Learning in Higher Education that compares two strategies--reading quizzes and "Readiness Assessment Tests" (RATs). Reading quizzes are a common feature in college classes, and they work well, the authors argue, when the instructor's objective is for students to learn the material in any way possible, or when there isn't enough time to score open-ended responses to the reading. But when the instructor's objective is for students to do the reading prior to class and be prepared to participate fully in discussions and learning activities, the authors recommend RATs. Administered at the beginning of a class or before class, students answer broad open-ended questions--not questions that students can turn to a specific page in their reading to find the answer. Typically, in a single RAT, students might respond to two or three such questions, and the answers are graded.
Both of these studies are on to the same basic idea: Hold students responsible and expect them to engage in higher order questions around their reading. You can even build these expectation as out-of-class work that will have the effect of turning your in-class activities into more fruitful experiences.