The online video collection produced by Annenberg Learner helps teachers increase their expertise in their fields and assists them in improving their teaching methods.. I have found these free videos, 1/2 hour to an hour in length, are useful for my own professional development and as a classroom resource.
My favorite series are:
- Earth Revealed (http://www.learner.org/resources/series78.html)
- Planet Earth (http://www.learner.org/resources/series49.html), and
- The Habitable Planet: A systems Approach to Environmental Science (http://www.learner.org/resources/series209.html), all appropriate for the high school classroom. The Habitable Planet also includes a supplemental website with additional resources such as an online textbook, interactive labs, and visuals (http://www.learner.org/courses/envsci/index.html).