They don't pick up these life lessons by themselves; that's what parents are for.
But when should the mystery of the toilet paper roll have been explained? When the child was 3? 10? Certainly by voting age.
Here then, after consulting many experts, is a brief guide to some of the tasks kids need to learn, and when their parents should be teaching them. And, as they say in those diet ads, your results may vary.
HOUSEHOLD Laundry: Start sorting clothes at 2 and help load and unload a washer or dryer at 3. Wait until they're 10 before they handle detergent or fabric softener, even a little older when bleach is involved.
Do the dishes: You can hand a 3-year-old a wet pot -- dentable but not breakable -- and a dish towel. A 4-year-old can load and unload a dishwasher, but keep them away from glassware and sharp objects. A 9-year-old should be able to handle it all.
Iron a shirt: Michelle Duggar, the mom on TLC's "18 Kids and Counting," has 10-year-old twins who iron. "They're capable of pulling the ironing board out, plugging in the iron and getting a few wrinkles out," she says. "Maybe it's not a perfect job, but they can do it."
Set a table: A 5-year-old can put out plates, silverware and napkins. As the child gets older, he or she can ratchet up the layout. By 12, with a little supervision, the kid could be setting out the good china, crystal, silver and linen napkins.
Trash: A 3-year-old can sort recyclables; at 7 or 8 a child can take out the trash.
Clean a toilet: Start them early, at 3 or 4, with a cloth moistened with alcohol to wipe the outside of the bowl and the floor around it. Hand them a toilet brush at 6, and by 9 or 10 let them graduate to a cleaner they spray on and let sit before scrubbing off.
Sew a button: There should be some familiarity with a needle and thread by 7 or 8. The Duggar boys learned to stitch a seam on a sewing machine by 8. "It's a machine," their mom explains.
Make a bed: A 2- or 3-year-old can make his or her bed. Maybe not perfectly, but good enough. The more they practice, the better they'll get. Kids should be proficient by 8.
Dial 911: By 5 a child should know how to call 911 and what to tell the emergency operator.
Change a light bulb: You spend years teaching them not to play with sockets and electricity, so wait until they're 6 before dealing with bulbs.
SKILLS FOR LIFE Tie their shoes: Age 4.
Shut off the water: Not at the tap, but at the main valve or at the toilet tank. Kevin O'Connor, host of PBS' "This Old House," figures 10 is a good age. "My main shut-off is so old and rusty; I'd be afraid of them breaking it if they got their hands on it any sooner."
Throw a circuit breaker: Also 10. "Might as well get them up to speed on all the systems in the basement the same year," O'Connor says.
Balance a checkbook/pay bills: They're too young to have their own, but middle-schoolers should know how to balance a checkbook, says Mary Suiter, manager of economic education at the Federal Reserve Bank in St. Louis. The same with paying bills. She points out another bonus of getting the kids involved: It reinforces math skills.
Use a house key: Age 6, says O'Connor. "The sooner the better. Saves them from sneaking back in through windows." Younger kids also can be taught to lock the door when the family is in the house and how to unlock a bathroom door in case they get locked in.
Tell time: By 6.


