"An open-ended question is one that does not lead and is appropriate when you want to engage another in a deep dialogue. True open ended questions have the following characteristics:

• They are focused on learning more about the individual, not about satisfying a need of the asker.
• They are asked neutrally, with no emotional charge, hidden suggestion, assumption or contradictory body language from the
  asker.
• They require some thought and reflection.
• They promote insight.
• They uncover opinions and feelings.
• They allow the question asker to be in control by
  steering the direction and depth of the conversation.
• They usually require more than a one or two word
  answer.

Closed questions can be answered quickly, usually without significant thought. Use them when you want a shorter conversation."

-Cheryl McMillan