This is a copy of an ATM poster that is no longer available. Its original title was:
Arbitrarily, just as they occurred to me, I have noted down a number of questions that may arise if one sets out to investigate space;
Why does a piece of paper fold along a straight line?
Why does a rolled piece of paper become rigid?
Why does a tied paper ribbon show a regular pentagon? ...
The poster is no longer in print. It was reprinted by permission of Kluwer Academic Publishers. Taken from "Mathematics as an Educational Task" by Hans Freudenthal (ISBN 90 27703321)