My 5 year old started learning this fall. I suggested that my mom start a project of the month club for her. She gave her a sewing kit as her birthday present and sends her a new project about once a month for her to work on. Here’s what we have done so far.
1 – sewing big buttons (like from Oriental Trading or Hobby Lobby) onto plastic canvas
2 – Lauri toys has lace a dolls that they can dress by lacing clothes onto them. This isn’t exactly sewing like you suggested, but my dd loves this activity for the car and it really helps her fine tune her fine motor skills.
3 – pieces of burlap with yarn and a large plastic needle and hoop to hold the fabric still. either free form or draw a design with a permanent marker
4 – make a needle case with felt
5 – sew a button onto a felt flower and then sew on a stem
6 – stick weaving
7 – spool weaving
8 – graduate into plastic canvas when she progresses past the burlap stage