When you look at the five components of reading and how teachers’ emphasis on them changes as students learn to read, one constant is word learning. This shouldn’t be surprising for those familiar with Scarborough’s Reading Rope, which suggests that vocabulary and background knowledge are essential components of skilled reading. These two strands of the rope can account for a 50-60 percent variation in reading comprehension scores. Not only do students need to know how to decode words, but they must also know the meaning of words in order to apply their meaning toward comprehension.
Washington Council of Administrators of Special Education