Photographing wadded up piles of bedsheets (muslin, no percale or satin please) would be great practice for them.
Yeah it would. They could practice stuff like Composition, Lighting, Exposure settings, and Shadow effects. And if the bedsheets are different colors -- hopefully not from 'skid marks' ;-) -- it could make for a decent Photograph.
(I see the weirdest things on Photobucket that people enter into the 'Photo contests'. It appears that some have never heard of the word 'Focus')