I've got a difficult classroom situation. I teach a required junior-level CIS course for non-majors. Perhaps 15% of the students are willing and able to do homework and study. Up to 25% of the class won't turn in required assignments. The majority of students don't have strong math/logic skills, but expect to skim through the book and understand everything.

I've already removed the really complex concepts and slowed the pace significantly. What techniques are effective to motivate the students to put more effort into their preparation? How can I better handle the classroom so that I'm not either boring the good students or baffling everyone else? My administration expects a 90% approval rate on the student's course evaluations.