Alex Case has written a great series of articles for English Language Learners and their teachers over the years, and has collected them in one post: The TEFL Why Oh Why series.
The seventeen articles include these ones:
Why did my foolproof activity just fail with that class?
Why your students don’t do their homework
Why does my teacher make us work in pairs?
Why does my teacher make me read silently?
Definitely worth a visit!