Adjustable Elastic Waist

My kids are so, so skinny. And I'm normally able to find adjustable waist pants at the thrift shop (where I buy all their clothes-why spend more than $1 when the kid is just going to get paint/pizza sauce/grass stains all over?) but sometimes I end up with a pair that isn't adjustable. Which means the kids go around sagging their pants. Not a great look for a teenage boy or a toddler. Thank goodness for Julie-K and her tutorial. She shares how to add an adjustable elastic waist yourself!See the tutorial here.