

Pretty simple: go to any big lake and close to the water level and then watch ships appear from the mast.
Or take any stick, place it perpendicular to the ground and measure the shadows length at noon. Then drive at least 400 km to the south or to the north and repeat the same measurement at your new location on the next day at noon again. Then compare the two lengths.
Or buy yourself a nice telescope, watch the other planets a and take a guess which form earth has, when all the other planets are round. Also: isn’t the normal crazies’ argument that earth is flat instead of non-round?




OK, while I thought that might habe been one possible interpretation, I didn’t want to miss if it was indeed serious.