This summer I acted as the "neighborhood fair coach" for some girls, and it was a lot of fun. We didn't get as far as quilting, but the 9 year old did some machine sewing, and younger ones did hand sewing. Everyone did crafts.
What I gained from the experience is that children are individuals with varying abilities and aptitudes. They respond to different approaches and need varying levels of supervision.
As far as hand sewing goes, using a quick practice project on plastic canvas (which looks more like needlepoint) worked great for children who had never held a needle in their hands before.
Best wishes with your endeavor. Time spent working with a child is very rewarding.
Dayle