No, this is not yet another salvo in the reading wars, because I don't care where you fall on the pure phonics -- just take your holistic guess continuum, you have to believe in the power of content knowledge.
There's plenty of evidence of the importance of content knowledge, though I'm partial to the old baseball experiment, in which it turned out that students have a higher reading comprehension level if you ask them to read about topics where their content knowledge is strong.
This doesn't seem particularly mysterious. Sounding out words isn't all that helpful if the sounds add up to a word I've never heard before. And my ability to form an educated guess is limited to things I actually know something about.
Unfortunately, the high stakes testing area has asked us to think of reading as a collection of "skills" that are sort of free-floating and unattached to actual content, as if "find the main idea" is a task that can be completed by a third grader as easily in a paragraph about baseball as in a paragraph about the origin of consciousness in the breakdown of the bicameral mind.
And yet the stars are aligned to once again give the short end of the stick to content knowledge rich areas. Worried about getting those test scores back up (because that's how Learning Loss is going to be measured in their neighborhood), administrators are bearing down on reading classes. I have not yet heard of anyone repeating the worst excesses of one former principal in my old district; he took students with low pre/practice test scores and putted them in two math and two reading classes per day and pulled them out of math and science entirely. But plenty of administrators are hurting the cause in other ways. For instance, elementary principals like to stick history and science in lousy time slots-- last fifteen minutes before lunch, last twelve minutes before lining up for buses, only once a week.
Deciphering words without a connection to content knowledge is not only harder, but it's an unfinished process, like opening a door to nowhere. And not just a door to nowhere, but a door without hinges or a frame. Trying to teach reading without content knowledge is like teaching a student how to open a door with just a door, by itself, lying in the middle of a field. You can teach them the parts of the door and how a doorknob works, but it's really hard to operate the door that way, and not very fun or interesting. Love of reading, the most desirable outcome, requires an ability to understand and operate the door (decipher the words), but it also requires the door to open up on a world, not a blank nothing.
Look, tortured metaphors aside, this is an area in which I agree with people I often disagree with in other areas-- when the Board of Directors is ready to learn to read, I want the foundation to be built on tons of content knowledge and vocabulary. I don't give a rat's hairy tushy about their DIBELS scores, and I already know they can pretend to read (If you want someone to provide a dramatic recitation of "Mighty, Mighty Construction Site," I've got your guys right here). When they sound out a word, I want them to recognize it. When they struggle through a text, I want them to have enough understanding of what's going on to use a context to help them. I want them to grasp that the marks on the page correspond to actual Things in the World, and I want their teachers to help them fill their brains up with all the knowledge of all the things.
And not because content knowledge will help them raise their test scores but because the whole point of the written word is to transmit understanding and knowledge and ideas and feelings and insights across space and time, human to human. Content knowledge, rich and deep and broad, is an aid to reading because it is the whole point and purpose of reading. "Reading," whether by decoding or by best-guessing, without any connection to the world, is just a performative school trick that misses the point and purpose of language. Don't shortchange content knowledge so that you can teach reading. Teach children content so that you can teach them to read.