I’d not heard about this letter (hoax or not) but I did read the “I have a dream” speech in the prospect park skating rink.
Its a very eloquent speech and if nothing else, it should be taught, so kids can see how one can take an idea and truly bring it to life
(Not that yiddishkeit is short on well written pieces, but if you need to teach something secular, I suppose MLK is as good a choice as any)