When I was in grade 7 we got to use coloured pencils to underline and label the different parts of speech. I enjoyed both the colour and the naming of the parts. When I was teaching writing, I accepted the going theory that teaching grammar didn’t help people learn to write better; direct feedback on their writing helped students improve as writers.
I always felt a bit guilty because I liked knowing how the sentence worked, and being able to name the parts. I also felt a bit stymied when trying to help students understand their repeated patterns of incorrect grammar, because they didn’t have the language to see (and learn to correct) the pattern.
I was teaching writing to help them communicate, but I was quite aware that they would be judged on the “correctness” of their spelling and grammar in significant situations, like when they were hired, and in their on-going employment, and possibly in notes to significant others. (I am currently judged for using non-texting language while texting, so I know the feeling!)
I think teaching grammar punitively and unimaginatively is a waste of time. I believe helping students have a sense of how language is structured and the language to discuss it metacognitively is important. I found David Didau’s article on grammar made a lot of sense – http://www.learningspy.co.uk/writing/writing-is-magic-but-what-about-grammar/ I especially like his decription of writing as magic, and spelling as casting a spell.