A certain student passed all his school examinations and then went to a college to continue his studies. There he put his name down for a course in geography, but after the first lecture, he did not go to any more. The geography lecturer noticed that this student was always absent and thought that he had changed to another course, so he was very surprised when he saw the boy's name on the list of students who wanted to take the geography examination at the end of the year.
The lecturer had prepared a difficult examination paper, which followed his lectures very closely, and he was eager to see how this student answered the questions. He expected that his answers would be very bad; but when they reached him soon after the examination and he examined them carefully, he was able to find only one small mistake in them. As this surprised him very much, he went through the paper again twice, but was still not able to find more than that one small mistake, so he sent for the student to question him about his work.
When the student had come into the room and had sat down, the lecturer said to him, 'I know that you came only to my first lecture and that you have been absent from all the others; but now I have examined your answer paper very carefully and I have been able to find only one small mistake in it. I am curious to know your explanation for that.'
'Oh, I am very sorry about that mistake, sir,' answered the student. 'After the examination, I realized what I ought to have written. I would not have made mistake if I had not been confused by your firs lecture.'