Tammy, did this mom question every teacher in her or her child's past? Does she or her friend at JoAnn's teach quilting? Cutting material or birthing a child does NOT make her a professional. Is this woman normally confrontational? Some people are, unfortunately.
If she'd prefer to teach quilting 101, tell her to have at it. Or instead, she can choose to remove her child from your co-op and supplement the learning with something else...maybe a class at JoAnn's at her expense.
Maybe I'm just off base and maybe she can't afford the material. She could always go to Goodwill and purchase bed linens and cut them to the desired size! From what I hear on this site, there's a lot of bargains with the material at local donation stores or garage sales!