Guy help pretty please! an easy 10 points.?

well I asked this guy to the sadie hawkins dance at our school a few months ago, but since hes really shy and kinda isnt into dances, he just decided not to go. Ever since then, we have been smiling at each other in the cl we share, but we havent really talked for long periods of time, cause hes really shy. lol but I still like him and now its the end of the school year. and since I go to a big school, the chances of me seeing him are slim. Should I write him a note and give him my phone number so we can stay in touch? If yes, what should the note say?