We were learning a new sacrifice technique- foot behind opponent's knee, pull and fall backwards. We had gotten the idea, so Sensei had us turn it into a takedown- by having us roll backwards to turn it into a pin.
Richard did perfectly every time- no surprise; he's a brown belt and has done it before.
Beth and Caine had more problems. Beth would lose her inertia, so sort of struggled around sideways; Caine always spun in mid-air because he usually does that when going to the mat so he's face down- not what's needed here.
I did it halfway.
Literally. I tried to roll backwards, ran out of inertia halfway, and couldn't power myself over- beyond the perfect balance point.
To everybody's amusement (including mine), I wound up- three times in a row- with my legs straight up in the air, with me unable to finish the pin.