With one of our DGD, I helped her to make throw pillows. We took a nice sturdy solid fabric and she learned to do decorative stitching by following the grid she had done on her pillow top. She had brought a little friend along so they each made their own pillow.
Another DGD went to a sewing school with my daughter (her aunt). They did a simple pajama pants and a camisole. They also did a rag quilt and a simple paper pieced wall hanging (the jar block).
You could also let her make a doll quilt or wall hanging for her bedroom.
You have been given lots of good ideas. Keep it simple so she can succeed. Soon you'll have a quilting companion!