Actually, Bostonian, my son had no idea until today that it was considered a bad word. He is twelve, has no reference points in his own history that would make him think that it was a colloquial reference to anything other than just being icky. My generation considered that word to be a borderline cuss word, but I can promise you that his generation does not. It is the same a yuck or ick or bummer.
Words he knows to be cuss words would never show up in a class assignment.
The teacher was just as offended that he used the word hate. He does not understand why he can't express a strong emotion about something and why the words "very strongly dislike to the point of abhorrence" would be ok but not hate.
However, to avoid similar situations in the future, perhaps you could send me a list of words you find objectionable.
A teacher is supposed to provide a comprehensive list of "4-letter" words? I think that's absurd. The obvious rule is that students are not to make colloquial sexual references in school assignments, and even a non-gifted child should know that.
