I grew up only knowing flat sheets and was puzzled and amazed when got to the Uk and found this fitted sheets.
No more struggling to do the bed in the morning, because they always stayed in place.
My only concerned and problem was when it came to folding it, nice and neat.
Someone with a lot of patience toke the time to teach me how to do it in such a way I would not end up inside of it.
1 - Lay the sheet on a flat surface - it is easy to start with - and straighten into the shape below