JokesMarriage Little Johnny’s Humorous Take On Chemistry Class. Little Johnny’s Chemistry Confusion. 2.7k Views Little Johnny’s teacher asks, “What is the chemical formula for water?” Little Johnny replies, “HIJKLMNO”! The teacher, puzzled, asks, “What on Earth are you talking about?” Little Johnny replies, “Yesterday you said it was H to O!” See more Previous joke An Older Man, Living Alone. Next joke A Woman Was Taking An Afternoon Nap.