Clean and tidy your bedroom. It is not rocket science is it? But somehow I fail to get them to understand that it means (as examples):
Rubbish gets thrown away not just put in a pile
Throwing stuff under the bed/in the draw is not the same as tidying
Cleaning needs to involves things like a duster/hoover
etc etc
They are (relatively) house-trained for most other areas and tasks, but this final hurdle I just can't crack.....