Unprepared.
How to get students to read the chapters.
When I assign certain pages for discussion, it prompt students to read. Students want to participate in classroom discussions. Therefore, it is not a strain reading a pages vs a chapter.
I tell my students to be prepared for a quiz on any given reading assignment. I don't always give a quiz, but I do occasionly throw one in to keep them on their toes.
My strategy for the students reading the material is to have the visual assignment to go along with it. They are each given a skull and in order for them to complete the assignment, they have to read the chapters to get the needed information.
One of the ways to get the students to read the chapters is by preparing mini quizzes that the students can come to expect every time they show up for class. You can address these mini quizzes in the syllabus as participation points and encourage the students to be prepared; these participation points could make the difference of one grade or another at the end of the semester.