Hand painted tree rings - would recommend putting all tree rings on a board (which could be painted a coordinating color to add pop to the art piece. Really neat idea for after school kids. Might just do 9 rings in a square frame!
Awesome Solar System Quilt - looks a little tricky but not as time-consuming as hundreds of tiny pieces - sew planets and stars onto the blue base, then quilt in circles/a spiral. Pinned for Kidfolio, the parenting mobile app that makes sharing a snap.