WHUT. Seriously, who bans dictionaries from school? Just because one kid looked up "oral sex"? Are we going backwards in progress here? It's the twentieth first century and it's America, for fuck's sake. He was going to find out what oral sex was with or without that dictionary. It's inevitable.
(Y'know, instead of complaining to the school district about how your child looked up a word in a dictionary, maybe a sex talk should be given instead? Waste the energy to something meaningful! I'd prefer for a kid to know what sex is and its purpose than being withheld the opportunity to take a dictionary and use it for help on his homework any time he or she needs it.)