Here is an effective approach for any school:
Every day the morning announcements END WITH A QUESTION designed to prompt reflection and responsibility in students. Posing a daily question directs the attention of everyone in the school (both students and teachers) to a specific issue or topic. Throughout the year, the school reinforces school-wide procedures, solves small problems, and encourages internal motivation through the announcements.
The school sees a lot of good coming from these questions because they provide a powerful way to influence students.
Kerry in British Columbia shared this idea.
Sample announcement questions are posted at her blog.
See Kerry’s categorized posts.