This did not happen on an exam. It was an assignment for art class. (I was 13 years old at that time, so more than 30 years ago.)
The assignment was very open:
“Make something beautiful and something ugly.”
We actually got the assignment upfront so we could think about it and bring the necessary materials to class. We worked on it in class for one lesson and had to finish it at home if it was not finished. So we needed to turn it in the next week.
I remember that someone of my class made a drawing of a flower in two versions one normal and one withered version of the same flower.
His withered flower was actually so perfect that it was hard to tell which of his versions was the beautiful or ugly part of the assignment.
I made the same object in clay but drilled holes in the ugly version .
Next week we had to turn it in. Unfortunately one of my classmates forgot his task at home.
But he found an elegant solution. He took two blank sheets of paper, wrote his name on both of them. Subsequently he crumpled one of the sheets and turned that in.
He got the highest grade of the class (together with the withered flower.)