One of the fundamentals in education is asking questions and receiving answers. Often the answers can end up being of the GWIT (Guess what I’m thinking) kind, and can be useful for checking superficial understanding. But if we want to promote thinking and deeper learning, we need to ask more searching questions, by raising debatable issues and introducing problems which might not even have answers.
The idea of asking questions which do not have a simple, “right” answer links to the idea of developing a culture of error. When all answers are accepted and discussed, students are able to risk giving their ideas, thereby giving you and themselves valuable feedback.
This cheat sheet from the Global Digital Citizen Foundation (globaldigitalcitizen.org) provides a number of useful questions which can promote thinking. If you are interested in following this up, they also have a booklet with introductory critical thinking exercises which you can download from their resources page (you will need to register for free).