Here's an easy one. Most likely when you were growing up you were told and even by observation - that boats/ships disappear over the horizon because of the curvature of the earth. Yet, if you had a telescope or even a camera with a high power zoom you would be able to still see the ship. The ship had not "disappeared" over the horizon because the earth is flat.
I don't know any airline pilots but if you do, ask him/her if pilots adjust for curvature of the earth when flying over the oceans. Oceans are flat and level but according to the globe earth model, they must follow the curvature of the earth. Therefore in order to maintain a steady altitude say at 30,000 feet a pilot would have to consistently be pushing on the yoke in order to just maintain that altitude.
Even if you don't know any pilots, just ask yourself you can feel the upward tilt of the plane upon takeoff and you can feel the plane level off when it reaches its cruising altitude. After cruising altitude is reached the only time you can feel the nose of the plane tilt downward is when the pilot begins to make descending movements as the plane nears its destination.