Can you imagine a strip of paper that only has one side and one edge?

There is such a thing, and it’s called a Möbius Strip. Here’s how you make it.

• Cut a fairly long, thin strip of paper.
• Put some glue, paste or sticky tape on one end.
• Twist it once and join the two ends.

This is what you’ll get –

• Now, with a pencil draw a line down the centre of the strip.
• Keep going until you meet up with the beginning of the line again.
• You will see that the line is on what you thought was both sides of the paper!

• Now draw a line right at the edge of the paper.
• Keep going until you meet up with the beginning of the line again.
• You will see that the line is on what you thought was both edges of the paper!

So, the Möbius strip only has one side and one edge.

• Now take a pair of scissors and cut lengthways down the middle of the paper.
• Keep going until you have two pieces of paper.
• What have you got now?

According to Wikipedia, the strip was discovered, independently, by Johann Listing and August Möbius, both in 1858. But it had, back in the 3rd century, already appeared in Roman mosaics.