My son and his friends are all 4, so they play in the playroom and then about 15 minutes before time to leave, I'll go in the playroom and say "Ok guys! Pick ONE toy that you're going to play with after we clean, and put it over here. Now let's put everything else away quickly. The faster we clean up our mess, the more time you have with the toy you picked out. And then I help, and encourage. We've got a 8 cube shelving unit from Ikea, and we bought crates for each shelf, and each crate is for a specific type of toy. I will say "Ok, all trains! Bring all train stuff here!" and we'll gather up tracks and trains and dump them in that crate, then move on to tools, action figures and dinosaurs, etc. You can tell that some children don't clean at home but I have found that if you "help" and call out what needs to be picked up next "dinosaurs!" and say it in a matter of fact but fun voice (think fun coach, not sugary sweet neighbor lady), the kids pick up, the room is clean in 10 minutes, and they can have some time to play quietly downstairs with a toy of their choice. Another option when I would provide short term childcare (like 30 minutes) after school for a few children would be BEFORE they arrive, I'd have something ready for them. Sometimes some watercolors, clay projects, or a roll of butcher paper where they can do some drawing, coloring, finger painting, etc...sometimes a snack and Looney Tunes shorts, sometimes balls or some type of backyard game or activity, sometimes just ONE crate of toys brought down.....that way the pickup is minimal. My rule is that my son knows he needs to help pick up, especially whatever he was playing with. It's only "fair". I also don't think it's wrong to have the other children pick up their messes as well. The more rare their visits, the less I'd push it, but if they are at your house everyday, they can be part of the everyday routine, in my opinion. Now what I don't know: When (a little older), should your son use his own voice and you not be as involved? Not sure. But I'm thinking that I'd be involved at first, to make it a habit, so the guest has an idea that this is an everyday thing and this is what is expected. After that, you can try to back off and see how it goes?