The author of a study that was sponsored by the National Council of Teachers of English died in 1931, just before the study was released. In it, he said the following:
“Probably no study is allotted more time and is more barren of results than that from which our grammar schools derive their name. After five or six years of grammar work in the elementary schools; after endless diagramming (which is but parsing in pictorial imagination); after painful memorizing of rules and definitions; and after constant composition of illustrative exercises, many a high school freshman cannot write or speak a decent English sentence.” Eighty-five years later, we are still trying to teach language via rules.
I asked a Spanish teacher who had several piles of worksheets by him, all covered with red checks, why he kept giving out worksheets when the students obviously did not understand what they were doing. “They have to learn the grammar somehow”, this native speaker of Spanish replied. “Well, do they”, I asked. With a sheepish grin, he said, “No” and kept on applying the red check marks until he retired.
The NCTE study is cited in The Story of Ain’t by David Skinner.