Can you see that?
We're not doing that again. Answer these questions:
If the earth is a flat disk, why is half the surface always in daylight, while the other half is always in darkness?
That is only possible if the earth is a sphere.
If the earth is a flat disk, how is it possible to observe the sun rise from the eastern horizon, arc overhead throughout the day, then drop below the western horizon each night?
That observation isn't possible, unless the hypothetical disk shaped earth is oriented perpendicular to the sun. One side of the disk would experience full sun, while the reverse side of the disk was in full darkness.
It means that the entire known world would be in daylight from sunup to sundown. We happen to know that that isn't true, which can only mean one thing:
The earth is a sphere, and not a disk. In addition:
The phases of the moon would not appear as they do to us, if that object were a flat disk. A spinning, disk shaped moon would present an entirely different picture to earth-based observers. It would look more like the iris of a cat, opening and closing throughout each month.
Explain why direct observations of the moon show it to be spherical, when it is not.