This site has great math projects. This can be done with nails in a board and colored yarn. Makes a great pricture too.
Paper ornament. Gloucestershire Resource Centre http://www.grcltd.org/scrapstore/
DIY Leather Knot
How to Make a Macrame Ring - Macramé Tutorial [DIY] - http://mysilverjewelry.org/anklets/how-to-make-a-macrame-ring-macrame-tutorial-diy/
Tutorial - friendship-bracelets.net
how to make knot cushion
40 Strings, 4 Colors
DIY bracelet/ necklace - macrame styles. Finally, been looking all over for how to get the moving out of square knot style.