Well, of course you haven’t, but in case some turns up, here’s a great way to spend it.
It’s is a video of a management training workshop by Marshall Goldsmith. He demonstrates an activity for developing skills in giving (and receiving) feedback – useful skills for work and for life in general. It lasts a little over an hour, but seems well worth the time investment if you can then integrate the activities into your classes. Plus, he’s pretty entertaining.