I've had 8 and 9 year olds sew a number of things -- Paper pieced Santa block sewed onto a sweatshirt, quilt block sewed onto pre-made tote, a tote, fleece headband, fleece scarves, shorts, life size doll that can wear their clothes, pillow cover made from a single simple quilt block.
By 9 most kids will have the manual dexterity and attention span to cut and sew quite well. Ironing is one thing I wouldn't have them do.