What about a tube quilt. Eight fat quarters cut into 5 inch strips sewed together all the strips and sew the first with the last. Then cut 5 inch strips from the tube. Then cut the strip apart a a differnt block and sew back to gether. A really nice size quilt to watch TV with. They can do the pillow turn after layering with backing batting and top. Then tie with yarn or embrodery floss. I have worked with several girl about the age of your granddaughers and they really enjoyed this quilt. Have fun with what ever you decide.