Hello. I did the same mistake and took an hour to get it.
start with circle, normal flipped,recalculate normal made it right.
but I don't still understand what it means. why the normal influence the mesh's rotation..?
I took screen shots that showing a part of normal looking at inside of arm in the wrong example.
I should stop thinking too much and move forward for now.
dduketogo Since mesh faces are single-sided planes (with no thickness) by nature, the normal determines which direction the face should be displayed. It can be weird to understand this because we can't physically recreate a single-sided face in reality.
Everything in our world has dimension to it, even a piece of paper, which is an obvious comparison to a mesh face. A piece of paper has thickness to it, however very thin. So it's actually a cuboid shape with 6 sides. For that reason, a piece of paper is viewable from all sides whereas a mesh face is only viewable from the direction its normal is facing.
But in the computer we can reverse the normal direction to tell each face to display in the opposite direction. In a way, it's like turning a shirt inside-out.
Again, it can be weird to understand face normals since we can't recreate it in reality..but I hope that explanation helps.