Albert Einstein had just administered an examination to an advanced class of Physics students.
As he left the building, he was followed out by one of his teaching assistants.
"Excuse me, sir," said the shy assistant, not quite sure how to tell the great man about his blunder.
"Yes?" said Einstein.
"Um, eh, it's about the test you just handed out."
Einstein waited patiently.
"I'm not sure that you realize it, but this is the same test you gave out last year. In fact, it's identical."
Einstein paused to think for a moment, then said, "Hmm, yes, it is the same test."
The teaching assistant was now very agitated. "What should we do, sir?"
A slow smile spread over Einstein's face. "I don't think we need do anything. The answers have changed."
Source: Thanks to Roy Petitfils for putting this story my way.
Dr Geoff Pound
Image: Albert Einstein