Wait time is important because ti gives students to formulate their thoughts.  At the end of “wait time” students will have collected their thoughts, and in most likelihood provide a better response.  As discussed I also think allowing an appropriate amount of wait time without giving them too much or too little time is important. If you are waiting too long, thinking to myself “what are they lacking in order to be able to respond” is an important meta cognitive process. Trying to get some of the more advanced students to answer first is another good strategy. This gives the others additional time to think without singling them out.