I normally sat up front (next to the exit) but got told to change with someone at the back. The greenboard was covered in the teachers yellow chalk lesson which we were copying. I moved to the back and looked up at a totally blank green board. Got up and walked slowly towards the front. About halfway the yellow writing started to appear. So I took a step forward, a step back, watching the writing magically appear and disappear. And that is how I became a 4-eyes.