I’ve always enjoyed mobius strips. We used to make them when I was young – a “wet Sunday afternoon” activity in the days before computer games and mobile phones. Well, to be totally frank, in the days before home computers were ever thought of, outside science fiction.

What you do, is cut a strip of paper about an inch wide (2 cm) and a foot long (30cm) and join it to make a loop. The important part is to put a twist in the paper before you join it. If you now start drawing a line along the length of the paper, in the middle, you will find that you go right round “both” sides of the paper before you join up with your starting point. Now, don’t stop here. Take a pair of scissors, and cut along the line you have just drawn. Prepare to be baffled.

http://en.wikipedia.org/wiki/File:M%C3%B6bius_strip.jpg

If the weather hasn’t improved, make some more strips and experiment. What happens if you start drawing your line one third in from the edge? What happens when you cut along this new line? What if you add more twists befor you stick the ends together?

When you are ready for a rest, watch this video.

https://www.youtube.com/watch?v=xUHQ2ybTejU&feature=youtube_gdata_player