One thing I found while using the Hack Clock as a teaching tool was that the kids are a whole lot anxious if there is an easy way to backup your work and restore quickly to a working version. For that, I've created an initial implementation of backups and restores within the Hack Clock interface - just hit the "load" button in the code editor and you will be presented with a list of backup points. Restore one and it will load it up within the code editor.

Much less stress for everyone, and a more fun way to experiment safely with changes!