My third year, my tenth year, and my eleventh year.
The third year was by far the worst incident of the three. About 20 minutes before the kids arrived, I turned on all nine sinks and sat down to get some work done. (Science teachers in my school had to do this every couple of weeks to keep some foul smell from making its way out of the drains). The sound of nine running sinks filled the room - loud, although somewhat relaxing. After about 7 or 8 minutes, I got up from my desk to shut them off...
My tenth and eleventh years involved incidents nearly identical to each other. A new project-based curriculum involved 7th grade science students growing basil hydroponically - without soil. (Pretty cool - learn more here). Plants were to be suspended in nutrient solution, which would flow from tank to tank via pumps. Anyway, I helped one of our 7th grade teachers set up her pumps just in time for her first class of the day...
Those were the three times I flooded classrooms.
The tenth and eleventh years were minor, as far as floods are concerned. They were cleaned up in a matter of minutes, although there were kids in the room both times. My third year was a very different story. Unbeknownst to me, a couple of the sinks had paper towels left in them, which clogged the drains. That year, I didn't flood one classroom - I flooded two. Mine was cleaned up and ready to use that day. The one below me was out of commission for about a week. (Did you know that ceiling tiles fall down, one by one, when soaked with water?).
I like to tell stories like these at the start of the school year.
"Hey kids, don't worry if you make a mistake in here. Listen to this."