When I work with high school students in my writing classes, I see tangible improvements in grammar and punctuation usage. I see the ability to compose a paragraph come to life. I also see timed essays worth scores of 5 and 6 but for one thing: spelling errors galore.
Is it common for students to make great strides in grammar, punctuation, and other writing skills but still not be able to spell their way out of a wet paper bag? It certainly is. Spelling occurs in a specific part of the brain. Handwriting has its part, and composing (getting thoughts on paper) has its part. Structuring sentences, choosing words, using punctuation, typing, and so on, each use a different part of the brain. Insisting that the act of writing — complete with proper spelling, grammar, and punctuation — is one big skill that a kid can master simply by writing more is one of the worst forms of educational malpractice out there.