Expedit and baskets. Now called Kallax? (Have no idea why)...
HOWEVER, I have to say that really the only way to keep things clean is to
* have fewer things (the most important)
* have a super simple organization system
* make them clean up after every play session (their little brains cannot fathom cleaning up a chaotic mess)
* help them clean up
Which brings me again to just having fewer things.
