A while ago I wrote a simple article on my blog. It was about our perception of Earth's curvature, and using some simple maths and geometry (Pitagorean theorem mostly) I tried to show that we're simply too small to perceive the aforementioned curvature.
Then I got some comments from flatearthers and it stroke me as absolutely fascinating, that it looks like those people completely lack spatial imagination. They seem to stumble on most basic and simple geometry on the level of elementary school. In fact it recalled me some of my own pals from my elementary and high school, who always got stuck on calculating shapes more complicated than square. Not mentioning solid geometry or trigonometry.
And... well that's it. Just some random afternoon babble...