Sugar on a Stick is a Fedora-based operating system featuring the award-winning Sugar Learning Environment and designed to fit on a USB thumbdrive ("stick"). This makes the Sugar Learning Environment deployable for the cost of a stick rather than a laptop; students can take their Sugar on a Stick thumbdrive to any machine - at school, at home, at a library or community center - and boot their customized computing environment without touching the host machine’s hard disk at all.

http://sugarlabs.org - open source educational learning platform.