What happens when schools don't use grammar and vocabulary to teach reading comprehension?

Reading comprehension is the key to everything. And sentence comprehension is the key to reading comprehension. To understand and respond to an entire text, students must first comprehend the words and sentences that convey its meaning. And in order to understand  complex words and sentences, students must understand the parts of words and the parts of sentences. To comprehend the whole, you must first understand its parts. Schools have abandoned the systematic teaching of word and sentence structures. The result is tragic: a generation of children who can neither read nor respond to the simplest of texts. ​