Math is one of the two major content areas that teachers focus most of their instruction on. English Language Arts (ELA) is the other. It's pretty common to find a teacher, especially in the K-2nd grades, spend 90% of each school day on one of these two subjects.
In the introduction of the K-12 standards guide for ELA, it says:
The ability to communicate well - to read, write, listen, and speak - runs to the core of human experience.
Reading, writing, listening, and speaking are not disembodied skills. Each exists in context and in relation to the others.
Which I'm cool with. Actually, just these two quotes encompasses the main purpose of ELA. But it probably goes without saying (even though I'm saying it anyway) often times, students don't receive ELA as pure as these ideals.
Personally, I prefer to teach ELA through the other subjects, rather than just by itself. Perhaps I'm not experienced enough, or have enough content background, to make ELA lessons quite as meaningful without relating it to authentic text. I despise using anthologies or abridged works as sole ELA resources too. There is just so much better stuff out there to use!
Thus, we encounter problem #1: there is so much stuff out there that it takes the a Samson-like strength to plow through it all. Luckily, there are short cuts (read: other teachers who are willing to share). I'll go through the fifth grade ELA standards in more detail for the next two months' worth of standards Sundays.
Note: Although some stories are better from another author's take, like Nausicaa of the Valley of Wind manga vs. the original Nausicaa from The Odyssey, (or the princess that loved bugs). The fake back story to The Princess Bride has this same idea. These have their own educational uses too.