I was getting kind of tired of devoting half of my weekends to housework (okay, I've never NOT been tired of devoting half my weekends to housework) while everyone else in the family was outside having fun.
And then I thought, Isn't the whole point of having kids for the free labor? I mean look at family farms. And family restaurants. And Cinderella's family.
So about a month ago, I started putting them to work. First thing after breakfast, everyone cleans up all their crap that has accumulated around the kitchen and living room and mudroom and sunroom and bottom three stairs over the last week. And no, picking things up off the floor and piling them on the couch/table/chair does not count as "cleaning."
M gets sent up to his room to clean up an entire week's worth of dirty clothes that he drops on the floor. Four feet from the laundry basket.
E and Z divide up the downstairs tasks: vacuum the mudroom, living room, kitchen, and sunroom, and mop the kitchen floor. When they finish with the vacuum, M does the stairs and the upstairs rooms.
This does not happen without a great deal of whining, fussing, cries of "why do I have to?" and sneaking outside to ride bikes. But it does happen. As with everything in the household, E and Z trade off being the Helpful Twin and the Difficult Twin. The Helpful Twin sometimes even takes on extra tasks (like spraying the windows with vinegar/water and wiping them down with an old rag; of course, I don't know any kid who doesn't like spraying liquid out of a squirt bottle).
This also does not happen without a great deal of guidance and correction from me: You have to get into the corners with the vacuum. You have to get under the furniture with the vacuum. If something is on the floor, pick it up; don't just vacuum around it. If something is stuck to the floor scrub at it with the mop; don't just go over it once and call it good.
It pretty much takes as much time to supervise them doing the work as it would if I just did it myself (though I manage to do work as well, like clearing off my desk dusting, while they're at it), but in the long-run I think they will thank me for giving them a grounding in how to clean a house. And I know their future roommates and domestic partners will thank me.