13 points
to be fair it was more than 1 stick
9 points
2 sticks
When I was a kid my teachers told me that Christopher Columbus discovered the earth was round and that before him everyone thought it was flat. When I was about ~13 I read a short biography of Eratosthenes and it blew my little mind.
4 points
Sagan did a bit on this.
There were also wells and a lot of walking involved.