Listen to FREE, ONLINE ,daily, EarthSky.org podcasts...fascinating science, space and geography subjects! You may download the daily/weekly podcasts or embed their podcasts into a blog, etc.
I used them every morning with my 6th grades classes as a "listening" (comprehension) class starter. The kids listened to the podcast, jotted down a few notes about what they heard and we discussed the topic for a few minutes. The kids turned in their "Earth&Sky" notes every Friday...I was able to give them a comprehension and class participation grade from their work.
(turn off the music gadget in the sidebar if you wish to listen to the podcasts now...)