Measure and divide the paper into fourths one direction and thirds the other way. Fold each line backward and forward a few times.
Number the front and back of the paper in pencil, lightly, as shown. Then carefully cut a center flap along the dotted lines.
Fold the paper along the dark lines as shown, so the center flap sticks out from underneath and the right-hand column shows all 2’s.
Fold the flap the rest of the way around to the front and fold the right-hand column under again. (Shown as dark lines on the diagram.) This makes the front of the flexagon show 1’s in every square.
Carefully, tape the flap to its neighbor on the folded column. Don’t let the tape stick to any but these two squares.
