When my Grandson was 8 he would sit on the couch between my legs and sew. I'd put my hands on top of his and 'help' guide the fabric through the needle. I DO NOT let him use the rotary cutter, but he does pin the fabric together. He also went shopping in Grandma's quilt room to find fabrics for his dinosauer quilt. Nothing feels so good as having your Grandchild interact with something you love to do. That's what memories are made of.
I'd get a dark piece of felt, drawing sewing lines on it using a white marker, get a darning needle and yarn and some buttons with big holes and have him sew the buttons on and sew along the lines. He will see progress and maybe you can make something to include his handywork on.