Nice post on how to get students to take your syllabus seriously. First: write better syllabi. That was Part 1 of this series (linked on page). Then, find ways of making the syllabus an integral part of the learning in the course (the key purpose shift). I especially love this idea:
One of the major differences that separates expert learners (faculty) from novice learners (students) is the ability to see the frameworks in addition to the individual pieces. The frameworks seem obvious and natural to you; they do not appear so to your students.
Thus Lang suggests that the syllabus be more of an annotated guide to the course instead of simply a list of assignments. A great idea, if there were (1) enough time to write that much more so early in the year and (2) greater predictability about the schedule (at the secondary level, the schedule is often more malleable than at the college level).
Lang includes several other excellent ideas about how to use the syllabus as part of the teaching materials in the course. Worth the quick read.