More and more research seems to be showing that performance in school can be enhanced by physical activity. These two sites, Brain Breaks and Deskercises, will give you some great resources for short exercises that can easily be done during the school day. Some of these are purely physical, and some require some mental exertions. The key is to give your students an alternative to spending hours in their seats receiving information. For more information on the benefits of adding more movement to our students’ school day, you can also check out this 2009 story from NPR.
Thanks to my colleague, P.E. Coach Jason Sellers, for bringing these to my attention!