Someone wrote to me asking this question in reference to the last post. I think it's a great question. I'll try to answer.
1. Because M and K have difficulty with school work. They have a hard time succeeding at most tasks that involve reading, and they don't seem to believe they've done well even when we praise them to the skies. Physical work is something they're both good at and find it easy to believe they do well. They can get jobs done and accept praise for this sort of work more easily than they can for school work.
2. Because, being adopted within their memories, they sometimes aren't sure they're part of the family. Doing work that helps all of us is invaluable for their sense of belonging.
3. Because they volunteer for every job we need to do. I'm not kidding. We can't let them help with everything, so we want to carve out jobs for which they alone are responsible.
Lest you worry that we intend to work our kids to exhaustion--don't. Growing up, I sometimes had enough chores to stifle my social life; we don't want to go that far. But we do want our kids to feel that they are an important part of a functioning team.
We do use physical labor as a disciplinary device, but gently, and we only assign jobs that really need doing. We say something like, "Honey, I love you, but it's been draining my energy that you keep spilling soup on the rug because you aren't sitting when you eat. You can give me back my energy by cleaning the kitchen rug before the end of the week." (We assign the chore but let the child choose when.) Usually, learning to do a new task thrills the child. Completing it and seeing what a difference it made are further thrills. Finally, the child loves it when the chore is done and the offense is forgotten.
Although my chore burden was sometimes heavy as a child, I don't recall resenting my chores except in one circumstance: when it seemed they didn't make a difference. For example, I couldn't stand vacuuming a room that already looked clean. Fortunately, our family is pretty messy. Any cleaning chores we assign really make the cleaner feel satisfied.