Questions are a major tool in the classroom. They are important for the students to be able to communicate with their teachers. When a teacher plans questions to ask the students, it is important to know what the goal of asking the question is. Are you looking for the exact answer or do you want them to be able to discuss their feelings? Questions are important to critical thinking skills, as well as being able to master core concepts. Both of which are key to their learning. It is never a good idea to ask a leading question. That involves leading a question in a way that it suggests it's own answer. This does not give students the chance to think for themselves. It is alright to ask a student that has just answered a question, why they feel that way. This too will get them thinking. Discussion questions are good opportunities to get the students thinking. However, never ask more then one question at a time. You do not want to lead away from the original question until the students have had a chance to answer it. You also do not want to confuse the class. Ask specific questions that have few answers. It is best not to ask important questions at the end of class because students know when the class ends. You may not get an appropriate answer.
Make sure to give the students enough time to answer and never interrupt the student while they are answering. Show that you are interested in their answers. There is not a 'stupid' question. That is how we learn the best, by asking questions.