rf
You are new here, so welcome. When you post a question, you probably have a pretty good idea in your own mind what you are thinking of. Here we have no clue until you provide more information. When you post, include as much information as you can,so we can try and understand it.
When I was in highschool, my bedroom was in the basement (Hmmm...is it a basement or a bedroom... there was no closet?), and I had a couple of black lights. We used the blacklight crayons which you could not see until the blacklights were on. My parents had no idea 8)