Learning about DNA topology by playing with string

The only way I was ever able to get any kind of intuitive feel for DNA topology was to play with string, twisting it, wrapping it, untwisting it etc.
I made a video demonstrating some ways model DNA structures with string, so grab some string and follow along!

(also my first foray into youtube, I'm not sure if or when I'll ever post anything else there though, but I think this turned out ok)