Messy Kids?!?!?

This is what the boys bathroom looks like.  Looks like a tornado came through there.  There is stuff everywhere.  You would think that eventually they would get tired of looking at that mess and just clean it up.  NOPE.  It will continue to get worse until I say something.  Why cant they just clean up after themselves?  I don't know why I am having such a difficult time with these kids right now.