Ergonomics mode today. A stupid Quora question pointed to a better reverse question that I hadn't stopped to think about.
Quora question: Why are carpenter's pencils flat?
Better question: Why are OTHER pencils round?
The usual school desk is slanted about 10 degrees, so round pencils will hit the floor unless you keep them in your hand.
Some of those school desks had a routed-out groove at the top, but it didn't really hold the pencil. There were aftermarket solutions like big square erasers that fitted on top of the pencil, but those shouldn't have been necessary.
Labels: Asked better than asked