My sister, Ilene, gave to BBBH an "Infinity Scarf." Trade-name, I guess. Anyway, one glance at the beautifully-made fabric item assured me that it was a Möbius strip. I announced this information to the gift recipient at once. She was less than interested.
So I started with my standard seventh-grade presentation of the concept. A Möbius strip is a geometric figure which has only one side, and possesses but one edge. (She: So?) Clearly this was going to rival in difficulty the actual presentation to a seventh grade class.
It is lots of fun to make a paper model of this figure with its weird properties, for with a pencil and a pair of scissors some amazing results can be obtained. (So?)
I am now talking to myself. I did not even get to the rudimentary math involved, and that is the real fun! The advantage lies with the seventh graders, for they are a captive audience, and may not wander from the precinct at will.