Check out NASA's Digital Learning Network. We offer free video conferencing to schools, and we just started a program called Virtual Visits. You can request a special guest speaker related to specific content area. Check out the Event Catalog and Special Events at http://dln.nasa.gov to find out more!
Through distance learning technologies like videoconferencing and webcasting, the DLN connects students and teachers with NASA experts and education specialists. You will find numerous modules in our Event Catalog for all grade levels. DLN events feature science, technology, engineering, and mathematics or STEM content that highlights NASA missions and research. All of our events are free. Register for interactive events listed in our catalog or watch our webcasts.
Website: http://dln.nasa.gov