Alright so, whenever experiments have been tried on the surface of standing water, this surface has always been found to be "level". If the Earth was an actual globe, the surface of all standing water would be convex (measuring less than 180 degrees). This could be experimented to prove that the Earth isn't a globe. Not to mention that rivers that flow hundred of miles towards the level of the sea without falling more than a few feet (the Nile River for example) which in a thousand miles only falls a foot. Now, with the Earths "convexity", a level expanse of this amount is very... incompatible which is more proof that the Earth is flat. However, there's still proof that the Earth is a globe. So, if you could go to the Harbor, I want you to watch a boat sail to the Horizon. Watch how the ship not only grows smaller, but also has the "illusion" of it sinking. This should be enough to show that there is some curvature to the Earths surface. Now, watch an Eclipse. Pay attention to the way that the moon moves. It creates an arch as it moves. Could we say that the moon move differently only when there's an eclipse, but that's just nonsense.
Hope this helps!
-Kaitlin :)