Various sports are performed on giant gym mats. These tend to be only liftable by a team of people and thus very hard to stack up at the end of a class.
They rely on their great weight to stay put, although that doesn’t always work (I once broke my ribs on a gym floor when the mats parted during a vigorous tae-kwon-do session (white belt, yellow tab ;).
Today’s invention is gym mats which are only say 1m long and wide. These are small enough to be put away by one competitor.
To avoid them slipping around, due to their light weight, each mat has a recessed groove set into its perimeter.
This allows a rectangular array of mats to be corralled by a strong nylon belt (the buckle of which also fits into the groove, leaving nothing to fall on or trip over).