From the post:
But by 10th grade, being a good reader no longer means being a good decoder. Most kids are good decoders by this time. Instead, reading tests emphasize comprehension, and comprehension is mostly driven by prior knowledge–knowing a little bit about the subject matter at hand. (I’ve emphasized the importance of prior knowledge in reading here and here.)
All that time spent on decoding in the early grades, (and time not spent on history, geography, science, music, art, etc.) comes back to haunt kids in 10th grade and beyond.
According to Willingham, “a parallel phenomenon is happening in math” where we push drilling rudimentary algorithms at the expense of understanding mathematical concepts.
In the end, he comes to the very logical conclusion that, if we expect high school students to do well in those international comparisons, “the work must begin in early elementary school”.