I had a rather worrying moment the other day. Whilst packing up at the end of a class, one of my students turned to me and said "So, I hear you're active on a certain website?"

I froze. I didn't know what to say. I mentally listed through all the members here to work out who he could possibly be. No matches. I don't know why I find it worrying that my students might find out about my internet life, but I do. I replied with a hesitant "What are you talking about?"

He...