This is just for fun. One of our family's favorite songs to blast while driving in the van is "Why Does the Sun Shine?" by They Might Be Giants. You can hear it here. Click on "Hear the Complete Show" and then fast forward to about 14 minutes into the program. I'm sure it's probably available for download on iTunes or amazon if you want to share it with the kids.
A non science-related song I like commemorates my favorite president, James K. Polk. Fast-forward to 37 minutes, 40 seconds.