Having done numerous crafts with various age groups over the years I can tell you from experience you will likely have a wide range of ability and talent. When my oldest was 13 I would test drive craft ideas with my 7 year old and even then I would have some 13 year olds that struggled. Even at 8th grade there will be some that will struggle with even sewing a straight line, others will be at your daughters level.
If it were me I would choose the most simple block possible that everyone would do one of and then have two additional options for those that can and want to do more.