Hm, seeing the other replies to your question gives me a sense of what you might be looking for. I concur with the this person [arrow drawn to Kurama's reply] and suggest that you acquire chalk from the arts and crafts room. With out available materials I think chalk might work a bit better than graphite due to the mineral structure. It will also powder easily using an improvised mortar. I do not recall seeing clear tape in the arts and crafts room, unfortunately.