It's three weeks into a new pair of shoes and your child says, "Mom, I can't get this lace through the hole."

You look down at the fat, unraveling, striped, synthetic material and groan. Not only do the shoe laces unravel shortly after purchase, but they also refuse to stay tied. Like a salmon swimming instinctively upstream, the tightly double-knotted lace begins the opening ritual as soon as it is tied.

And once untied, it begins to self-destruct.

Kids' feet cause many problems. Shopping for their shoes can be one of the most traumatic duties of parenthood. If you enter the store thinking you'll but a pair of "good" shoes like you had as a kid, you're in for a shock. Your mom may have taught you that the one thing you don't scrimp on is shoes. These "good" shoes somehow guaranteed you'd grow up strong and healthy.

But today if you have several children who need shoes, good or otherwise, you may have to take out a second mortgage.

If a sturdy school shoe is not mandatory, you may think, "Well, we can make do with sneakers." (The advent of cold and snow are particularly chilling to parents. . . . They mean yet another pair of boots to fit over yet another pair of shoes.) Even if a special school shoe is required, you also will need a leisure shoe, for no kid would be caught dead in suede oxfords outside a school building or church.

So you head for a sports store, maybe one advertising a sale. You ask the clerk for "an all-purpose athletic shoe, preferably one on sale."

The salesperson is an incredibly fit, blond 18-year-old who smirks as he points out the features of each of 40 types of shoes that look remarkably similar. He looks at you like you are 75 years old and have been living in a cave for the last decade.

"These are for long-distance running; these are for indoor track; these are for basketball. . . . What will she be doing in them?" he asks glancing at your daughter.

"Everything," you sigh. "Could we please see the ones on special for $16.99?"

Looking down at her ravaged shoes he says, "The way she wears down her shoes, those might not last long. How old are those?"

"Six months," you say as your child pipes up, "No, Mom, remember, we got these just before Halloween."

The clerk holds up a pair of leather "sneakers" adorned with metallic stripes. Your kid's face lights up. As you spot the dangling $49.99 price price tag, you say, "Let's try the ones on special."

The next hurdle is fit. Naturally, the sale shoes are too wide and slip at the ankle. You finally settle on a confortable $24 pair and grumble when your husband asks, "They cost what?"

Kids' feet present another difficulty -- socks. The only thing close to shoe laces in self-destructability is tube socks. Whether you buy the package of 10 pairs for $2.99, or the anti-odor, anti-wear models at $3.50 each, they will have holes in them before you can shout, "My, I forgot how grandiloquent Howard Cosell is."

What's even more perplexing is that phantom who sneaks into everyone's clothes dryer and steals one sock from each pair. When our family prepared for school, we sorted out three children's socks. Altogether we collected 19 single socks. Sock manufacturers must change the stripe configuration and dye lots every few days to guarantee you'll never be able to find a match once the original pair is separated.

Colorful, striped, and patterned socks cause the same problem. No one buys two pairs of purple and silver knee socks; when one is gone, that's it.

Sports entail another hardship. The current generation has to be the most exercised group of humans ever raised. Organized teams begin in kindergarten. And with teams, comes the need for special shoes: cleats and basketball and tennis shoes that should never be worn off the courts. And because children grow each year, last year's shoes never fit this year's feet. And big brother's cleats are almost always too narrow/wide for little brother.

Another difficulty: The player should look professional. The tube socks must match the team jersey, a different color each season. And does your child get a nice red or blue jersey? No, his is purple, or black, or orange.

Most parents swoon with delight when their child tosses aside ratty T-shirts and jeans and opts for the preppy look, but preppy feet can be a disaster for the family budget. Have you seen the prices of those penny or tasseled loafers, deck shoes, and tan-on-tan saddle shoes?

Once you've struggled through the shopping and each child has something stylish and expensive to put on his feet, you consider your own slightly outdated, worn shoes and decide, "They really are classics. I guess I can get them resoled . . . again."

It's no wonder you go slightly berserk one morning when your child comes out ready for school with his toes peeking through the holes in his old -- and obviously crippling -- old sneakers.

"But Dad, my Nike's look too new."