To be able to do that "teachers" would have to teach American history in a positive light.
The precept that our Founding Fathers were nothing but "old dead white guys", unworthy of any adulation, comes with a price.
I was lucky. I had a 5th grade civics/social studies/homeroom teacher who added to the regular curriculum extra courses on American government and on our Constitution.
5th grade is when we're taught American History, for the first time, as a subject. Prior to then, tidbits of American History were taught in the context of other social study subjects. Without the extra courses, the social studies curriculum for that year would've only reinforced liberal revisionism of our history while not teaching anything about the fundamental documents that define our country.
So, yes - the problem is with the teachers. Forced recitation of the pledge has no meaning if those who recite it don't believe in it. Just as taking Holy Communion has no meaning if you aren't truly a believer or repentant.