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Polygon Rings

Age 11 to 14 Challenge Level:
Here is a pattern made of regular pentagons:

If the pattern continued, do you think it will form a complete loop or will the pentagons overlap?
Try it using the Tessellation Interactivity below. 
If you've never used the interactivity before, there are some instructions and a video.

Once you've had a chance to explore, here are some questions you might like to consider.

How many pentagons form a ring?
How many decagons would form a ring?
Why do they fit together so neatly without overlapping or leaving a gap?

What about other polygons?
Can you always make a ring?
Is there a way to predict how many polygons you need to form a ring?

With thanks to Don Steward, whose idea inspired this problem.