These are some of the things my kids do-
cut fringes off washed FQ
glue scraps onto pieces of paper (for toddlers)
sew on the sewing machine their own doll quilt (if they are very small they sit on my lap)
hand me pieces of fabric I need to iron
sort and fold
help with basting
My now 13 yr old is an avid quilter and she made her first quilt at around three. With my help ofcourse. Others make their first quilt when they are older. It all depends on how precise they are. Also I have them tie quilts well before they do quilting. I found hand sewing much harder then machine sewing for them to do.
Rotary cutting is the last thing I let them do. Now at 13 I let DD rotary cut under my watchful eye. I had a friend whose 10 yr old sister cut herself with a rotary cutter at a class at Quilt in a Day. Just not worth it to me.
Besure to do it all in small increments spaced over time. that way they keep enjoying quilting. do not forget their snacks and some of mom's/gram's chocolate treats.