If you are working with younger girls who have never had a needle in their hands, I would suggest some plastic canvas work (like needlepoint, but easier). You can work up to cross-stitch on gingham from there.
I helped a 9 year old neighbor girl this summer, and our first sewing project was a "scrunchie". The only hard part was the last seam - a cross seam that included the elastic. But it was a short seam, so that helped. It was a quick project where she could see the results and have something she could use right away.
Dayle