Most of the toy machines are more hassle then fun. Six is not too young to learn to sew on a real machine. I would suggest you let her use your machine. Draw a wide seam line on two 10" squares of her choice of fabric and let her make a pillow. She will enjoy stuffing it as much as sewing it. Put the foot pedal on a box so her feet won't be dangling. If the pillow is wonky, that's just fine. Don't try to make it right. That comes later.