"Resetting files in the index" lesson doesn't make a lot of sense.

[andrewsil1]

The purpose of the lesson is to reset two of the candles to an earlier (presumably non-blown out) state, and then commit so that only one candle is blown out at the end. However, the lesson starts with only a single commit in the index in which all of the candles are already blown out and there is no earlier state to restore from. So while you can "reset" the files and commit, nothing is ultimately changed after completion and the point (to the newbie) is sort of missed entirely.