What is your goal for carrying? If it's self-defense, then if you honestly feel the need to open carry there, you probably shouldn't be leaving your kid there.
If it's "intimidation", are you honestly the kind of person who wants to intimidate your kid's teacher?
Finally, where do you live? Is open carry very common there? If so, go ahead! If you live somewhere that open carrying will get the police called on you, you probably shouldn't. These are people you're leaving your kid with. I wouldn't want to freak them out on the first day. (Who knows, they might just choose to refuse to allow your child in to their program - I hope you have alternate daytime plans available if that is the case.)
Is open carry more important than common courtesy? I would love it if open carry were accepted everywhere, but it's not. Until it is, show self-restraint when warranted. (Then again, I'd also accept a complete ban on all guns, if the government could *PROVE* that *ALL* guns are gone, from *EVERYONE*, including the police. Which, of course, isn't going to happen.)