Zipper Bedsheets
Bedsheets are long and wide enough to fall over all the sides of the bed, and have slit on each side with attached zippers. Instead of fitting the sheet under the bed, the sides can be zipped to keep the bedsheet taut. Here, interlocked cardboard pieces demonstrate the zipper component.
The person can sit on top of the bed to hold the bedsheet in place as they zip down the side of the sheet.