# The twist flex

© Davidson Institute of Science Education, Weizmann Institute of Science

One of the simplest prime flexes there is, is the twist flex. Try it out for yourself!

• Download the template linked in the ‘related files’ section of this step (template number 13 in the flexagon booklet). Cut out the two templates for the back and the front and glue them back to front. Make the flexagon in the usual way, folding faces with the same color toward each other, starting from the highest number – so fold 4 to 4 and 3 to 3 until you have folded a square flexagon.

Note that the triangles that make up the flexagon are isosceles right angle triangles with angles: 45 45 90. The top (1) side is blue and the bottom (2) green. Flexagons that are comprised of isosceles right angle triangles are known as silver flexagons. So the flexagon in the template is a silver octa-flexagon.

• Mountain fold the flexagon in half.
• Hold the flexagon in your right hand with your fingers grasping the triangle on the right hand side – or at least keep it steady on the table, and twist the triangle on the left hand side. Open up to see a hexagon. The right hand and left hand triangles are blue, while the others are purple.
• Unfold along the long diagonal of the flexagon to get the final state – a red-green square.

# Discussion

Any questions? If so, please ask below and either myself or one of the other participants will answer.

© Davidson Institute of Science Education, Weizmann Institute of Science