“Which human organ becomes multiple times larger when it’s stimulated?” asked a sixth-grade teacher. Students looked at the teacher with a mix of puzzled and interested looks on their faces.

But Maria, one of the students, stood up and asked, “How can you ask such a question? “, her face red with anger. “I’ll tell my parents, and they’ll fire you!” When Maria yelled, the teacher was shocked, but she decided to ignore her and ask the question again.

Thomas, one of the students, got it right this time: “The answer is the iris in the natural eye.” Thomas got the right answer, so the teacher praised him. Then she turned her attention to Maria.

“I want to tell you three things,” the teacher said in a calm voice. First, it’s clear that you haven’t done your work. Second, your mind is dirty. Third, I worry that you will be very unhappy one day. The class laughed out loud at the teacher’s clever answer, and Maria learnt a good lesson about keeping an open mind.