Take some cardboard and trace an outer circle (smaller circle for smaller kids).
Make an inner circle in the center and another to form a border, with 8 even lines fanning out.
Cut along the lines, just between the circles. Begin weaving in and out between each segment.
Continue weaving alternate segments, punch holes around the outside and thread it all together. It takes a bit of time and dedication, but makes a lovely, simple hanging piece eventually.