But it is also impossible to tell if the person who accessed the content was a teacher or administrator (inappropriate use of school resources) or a student (improper filtering or inadequate security). If it was a particularly vulgar phrase, I would be inclined to believe the latter. If students are able to access your content, this is something that the school district might get in trouble for, but reporting it might cause more problems than it is worth - personally I would just block the offending IP and move on. If you report it to the school, they likely don't have the resources to track down the offender (they would have blocked the traffic if they did) but it might give them a wakeup call that they need to re-evaluate their network security.

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The best way to learn anything, is to question everything.