We were able to check out Schoolhouse Rock a while ago from the library and it was awesome! The disc contained all of the old songs from the 70's. I would love to own it.
I was going to find some of my favorites on youtube and link here. But it appears that some versions have been blocked due to copyright issues. I was able to find other (low quality) versions on youtube, posted by other users, but I didn't feel comfortable posting the links here.
So instead, enjoy this hilarious semi-"educational" song by Veggie Tales. So, it's mostly ridiculous. But I have seriously used this song to help my kids remember that chimpanzees and gorillas aren't monkeys.
Here's another fun one that I find myself quoting often- School House Polka: