LifeHacker has a good review on the recently released new version of Puppy Linux. To be honest, I've not heard of this version. I'm a fan of small form factors of Linux for older computers. This version is also designed to run from a USB flash device.
Running from a flash device can be a good feature for students who need the same application at home -- a likely situation if you're using Linux in the school. This removes the issue of not having the required application at home.