I have personally confirmed the roundness of the earth in many ways.

Buy two dowel rods of the same length and mount them to identical wooden bases so that the finished product is two identical rods pointing straight up that are identical heights. Get someone you trust to take one of them a couple hundred miles due north or south (not crossing the equator). Erect both of them at the same altitude and measure the shadows they cast at the same time. You and your trusted friend will have different shadow lengths because of the curvature of the earth.

Another thing you can do is fly somewhere with a different time zone with a watch and note that the time of sunrise and sunset doesn't match what it should be according to your watch. That's because you're at another place on a giant globe.

EDIT: The North Star (Polaris) appears to remain in one spot in the sky because it is aligned just about perfectly with the rotational axis of the earth. The other stars appear to be revolving around it because the earth is rotating, which is also why the sun appears to be revolving around the earth.

I have personally confirmed the roundness of the earth in many ways.

Buy two dowel rods of the same length and mount them to identical wooden bases so that the finished product is two identical rods pointing straight up that are identical heights. Get someone you trust to take one of them a couple hundred miles due north or south (not crossing the equator). Erect both of them at the same altitude and measure the shadows they cast at the same time. You and your trusted friend will have different shadow lengths because of the curvature of the earth.

Another thing you can do is fly somewhere with a different time zone with a watch and note that the time of sunrise and sunset doesn't match what it should be according to your watch. That's because you're at another place on a giant globe.