Sizes are a little difficult.
For S (girl age 5) today she is wearing:
Shorts with an elastic waistband in a size 10/12 and they seem to fit pretty good. I think if the waist wasn't elastic she may need a 14. Her shirt is a t-shirt size LG 10/12 and fits her perfectly.
J (boy age 10) is wearing:
T-shirt size XLG 16/18 (but I think he coulda actually use a size or two bigger).
Pants are a size 34x30. They seem a little tight in the waist, but kind of big everywhere else.
That's the best I can do in clothing sizes. Its hard to get proper sizes when they've only been wearing what they can find that fits.
Thank you, thank you, thank you ladies for offering to help!
I also know they are both very much in need of school supplies. Their mother was just commenting the other day she was hoping the lists weren't too long. School starts August 8th here.