There is a great example of this at my school. I have one teacher who appoints a student to be "Tech Help" for the class. When the SmartBoard stops working correctly or some other problem, the teacher (who is tech competent) just calls for Tech Help, please. The student then comes up and attempts a solution. Most of the time the student is totally able to solve the problem. Surely the teacher has done some prior training; what matters is that works.
In fact, "Tech Help" is a great way to show that this teacher has mastered a piece of the ISTE Standards for Students (NETS-S).
6. Technology operations and concepts Students demonstrate a sound understanding of technology concepts, systems, and operations.
a. Understand and use technology systems
b. Select and use applications effectively and productively
c. Troubleshoot systems and applications
d. Transfer current knowledge to learning of new technologies
The teacher could try to solve the problems herself and move on with the lesson (and sometimes she does), but, instead, she lets the students show what they can do.
So, whether she asks for "Tech Help" because the youngsters know more than she or because she wants to give them opportunities does not really matter. What matters is that the teacher is asking the only people younger than her that really matter, the students.