One of my 7 year old DD's regular chores is to help me with the mopping.
The way I started out doing it was that I would do the foyer, dining room around the edges of the rug, and back hallway, and she would do the kitchen. I soon realized that the kitchen was a little too hard for her, because of the chairs, under the lip of the cabinets and so forth. So I switched with her.
The first time she did the other areas, she said, "Mom, that was a lot easier!"
"Yes, it was, wasn't it?"
She stopped, pursed her lips and tilted her head, and said thoughtfully, "Huh. So, all this time I've been doing the hard part and you've been doing the easy part. How...awkward."