A college chemistry professor could not help but notice that one of his
students was late to class for the third time that week. Before class ended
he went around the room asking students some questions about the day's
lecture. Of course, he made sure to pick on his tardy pupil. 
 
"And who was it that discovered uranium?" the professor asked.
 
"I don't know," the student said.
 
"Perhaps if you came to class on time, Mr. Winters, you would know," said
the professor.
 
"That's not true," the student replied. "I never pay attention!"