A teacher is told that the principal of the school will be inspecting his class on the next day. Now, the teacher is worried for the impression that his class might cast on the principal since all the students are not intelligent. Also, the principal can ask questions from anywhere. However, he will have the power to choose any student for answering the question.
Now he wants that the principal must be impressed with the performance of his class. What will he do to maximize the final impression on the principal ?
Solution:
The teacher will use a simple trick to form a perfect impression. He will ask all his students to raise their hands on each of the question that is asked. But the only catch will be that those who knows the answer correctly will raise their right hand and others will raise their left hand.
In this way, the principal will see all the hands being raised for each question even though all won't be knowing the correct answer. The teacher will ask only those who know the answer and they will always be correct. So the principal will be impressed to full extent.