Oh, I've done that one too! Thankfully it seems to come off it you scribble over it in whiteboard marker, leave it for a few minutes and then erase.

Critical Analysis is complicated and very boring. I'm really regretting saying that I'd do 5% marks for attendance. I really don't want to be in there some days.

Also, in good news, corrections weren't as complicated or long as I was expecting. I'd thankfully saved it as many, many layers, so all I had to do was some tweaking. I shall be going to bed within the next hour or two ^__^