I was taught "the New Grammar" (to go along with the New Math) at my elementary school. We didn't have verbs or nouns or adjectives, we had "Class I" or "Class II" or Class III" words. The effect of this is that while I have a pretty fair seat-of-my-pants grasp of grammatical rules, I often cannot explain in terms comprehensible to people who are not Me, why I believe something is right.
Which leads me to my current project, preparing a Letter of Intent to pply for a grant for YG's elementary school. This is a fabulous school--everyone should immediately send it money. They educate some of the poorest kids in the city, 80% of them from immigrant families, and over half of whom arrive there speaking little or no English, and they do a superlative job. Honest. And because, of course, if you do things right with barely enough money, the Authorities figure you can keep on doing things right with even less money (!!) we are forced to support the arts program with foundation money and whatever sorts of fundraising we can do. (This is why I am the Boxtops4Education Goddess at the school....)
So, I wrote a sentence that went, "Despite the fact that our population is an historically low-achieving group, Moscone students continue to excel academically." Two teachers at the school, offering comments and changes on the Letter, said I should remove the N and make it "a historically low-achieving." Is this correct? It looks bad to my eye, and sounds worse, but in the end it's their proposal, I am merely a humble instrument. I'd just like to be able to explain why I think it's wrong using something other than "Class I" words.