Questioning is a powerful way of increasing student participation and encouraging understanding. You can ask questions during a lecture, when students work on small group projects, or when they are studying independently at desks or lab tables.
There is a difference between questioning that prompts students to think more deeply about their learning and questioning that requires recall of facts. The right kind of question at the right time can help a student clarify her thoughts, recognize a pattern, or overcome a conceptual hurdle.
Good questions can help teachers, too, by highlighting students' misconceptions, and can serve as models for students who are learning how to ask their own questions during scientific investigations.