One of the main problems with English (and I speak only from my own experience and from hearsay) is that schools simply do not teach it. The last time I was taught any sort of English grammar was in, I think, 4th grade (about 10 years old), and, even then, only incidentally. Most of it was in 2nd grade (8 yo, obviously) This is far too early to comprehend grammar. After that, it was all ``literature'' and ``creative writing''. Not that there's anything wrong with that, but there needs to be followup grammar once you've done a good amount of reading and writing and can now comprehend what a subjunctive case is, or what the difference between a direct object and a predicate nominiative is, and so on. I get the impression that other languages are taught to their native speakers much better. In fact, most of the grammar I know now comes from taking German classes in high school, which spurred me to learn more about my own language. (Comparative grammar is very interesting, BTW, for geeks like me.)