Dianna ,
This is not an unfamiliar situation. Depending what time your class is conducted, if possible try to get your guest to arrive first thing or last thing of the class. If they're first, you can adjust your time remaining better, and maybe reflect on what the guest had to say. If at the end of class, your student will appreciate a change in the routine, anad they'll be focused because they know that it for the day and the guest will be done as time will run out.
Barry Westling
