This is a really cool tool for 4th and 5th grade classrooms. It's called The Walking Classroom. The materials are aligned with the 4th and 5th grade Common Core Standards for Language Arts.
This is how the program is described on their website:
The Walking Classroom Institute is a nonprofit organization dedicated to improving the health and education of all students. The Walking Classroom program is an in-school obesity intervention that promotes health literacy and develops and supports lifelong fitness habits for all students while addressing different learning styles. The method combines standards-aligned academic content and exercise during the regular school day. Using WalkKits pre-loaded with a year's worth of standards-aligned audio content students walk, listen, and learn.
It is a bit pricey, $3,000 for a class set, but they do have scholarships available to apply for on their website. It would be cool to purchase and perhaps share with the other classes in your building. And the teacher blogs I have seen this mentioned on tell about how their students just LOVE it. After you get things set up, the podcasts are only about 15-20 minutes. Perfect for those inclement recesses or an afternoon break from the walls of the classroom and their desks.