From Chalkboards To Strollers: Autumn Scavenger Hunt For Toddlers and Pre-Schoolers - This is great for just paying attention to the world around you! And I think with older kids you could make it a race!
This is a fabulous way to get your students to familiarize themselves with all the different areas in the classroom. Also a great first day of school (wasting time bc you're finished with the rules) idea. For Pre-K I would use pictures with words.