Sempstress

Sometimes, you need a knicker, or some other relatively non-denominational short, slightly poofy pantlet with a cuff at the bottom, and you don’t have time to make it from scratch. (Perhaps, for example, you have a cast of 37, and 9 or 11 of them are kids in Fagin’s gang and most of them are too short for proper long pants… Hey, it can happen!) Here’s the cheater’s method:
Hie thyself off to Goodwill or some other charitable resale destination. You’re looking for women’s tapered, pleated pants. No, really, this is the one time in your life when you want to find this particular atrocity… For the record, a woman’s 6 is a good place to start to fit 8-12 year old kids of normal kid size. Go ahead and buy pairs that are in good condition, and don’t feel bad at all about the fact that you’re about to mutilate and render unwearable something that someone might otherwise have bought and worn – it’s a woman’s tapered, pleated pant, and you are saving someone from it. And you’re supporting a charitable organization. That’s double good karma points. (If you’re an overachiever, you can go for the triple score by involving a not-for-profit theater, charitable resale, and saving a stranger from bad fashion….)
Here’s the process:

Ye olde horrible pleated, tapered pant

Fold the pant neatly, as if to hang it.

Cut the pant leg an inch below the knee of the wearer. Logically, knees are about midway down the leg, but if you're working with children you should measure. Also cut off the bottom cuff of the pant - you'll need it in the next step.

Pin the cuff to the pant, right side of cuff to wrong side of pant. Sew, so the seam is on the outside. Flip cuff up, to cover seam. Tack in place at sides, so seam stays hidden.

Voila! They take about 12 minutes a pair, once you get the hang of it. Bonus: the offcuts from the legs can become sleeves without much effort.