♤ How can one prove that the world is round?

This website is introducing how prove the world is round.
The content in the textbook is based on Columbus' discovery.
Let's turn our view to science!!

◐ BEFORE YOU READ.
1. When did you know that the Earth is flat? How?

Let's read this article (^________^)

http://www.physlink.com/education/askexperts/ae535.cfm



this is about scientific opinion, but not that difficult.

just TRY to understand!!!

◑ AFTER YOU READ
1. The writer also mentioned the Columbus' discovery.
Can you elaborate more than the textbook based on this article?
2. how did The Greeks discover the Earth is not flat?