Earlier this week I saw this in Mrs. Webb’s classroom.  I loved it and asked her – where did you find that?  She promptly told me she made it.  And it is so simple.  Scroll down for instructions.

Materials:

tree boards (Hobby Lobby)
nails
a bag of stretchy bands (like you use on those looms for potholders)

If you study the photos – you can see Mrs. Webb drew a grid.  She hammered the nails into where the horizontal and vertical lines met.

Viola!  Done.

Thank you Mrs. Webb!