Flat Earth?

Can someone explain this?

I wrote a longer article showing how to check for yourself if the Earth is flat, but here’s a simpler, quicker, and more direct argument.

Pendulum’s swing back and forth in a fixed plane, but over time that plane rotates around. In fact, at the North and South Poles the plane swings around exactly a full circle in one day, as the Earth rotates in space a full circle underneath the pendulum.

At the equator, a pendulum’s swing does not rotate around at all.