Zoe, who is now five, sews on one of my Singer machines. I make sure they first know how to wind and insert the bobbin, and how to thread the machine. Sit them down with a few sheets of lined notebook paper and let them stitch (even without thread) along the lines. This certainly helps them learn control for a straight seam. The 6, 9, 11, and soon to be 13 year old DGD all sit and sew. Funny how their personalities come through - the oldest is the least careful and the 9YO is the pickiest. The 11YO gets discouraged if it doesn't go right, but isn't willing to rip things out or make corrections.