Educational psychology tells us that students (middle and high school) do not naturally ask themselves metacognitive questions. We need to help them develop this skill! I love this application specifically for math-in-context problems, but it's great for all subjects.
Check out the one page poster to use in your classroom as a guide for students. (And don't just put it on the wall... few people read those.) Build the questions into your own vocabulary and help students return to them regularly as they become tenacious, independent thinkers.
Related article from eduTopia.