If you are in the mood for an excellent science podcast that is also kid-friendly for middle school and high school students, I highly, highly recommend the Skeptic's Guide to the Universe Podcast.
Skeptic's Guide to the Universe Podcast
In fact, if you only have time to listen to one science podcast per week, I would put this one at the top of the list. There are other excellent ones out there, but if I had to choose just one, this would be my choice.
The Skeptic's Guide to the Universe is a weekly podcast hosted by Steve Novella, Jay Novella, Cara Santa Maria, Robert Novella, and Evan Bernstein. Past hosts include Rebecca Watson and Perry DeAngelis (deceased). I've been an avid listener for about four years and look forward to new show each week. Episodes are approximately an hour and half in length and have recurring series such as Forgotten Heroes of Science, Who's That Noisy, What's The Word, and Science or Fiction.
I particularly enjoy the Science or Fiction segment which takes place at the end of each episode. Four science news items are given and you have to figure out which three are science and which one is the fiction. It really gets you thinking!
So check it out. Science lovers will LOVE this podcast!