Here's a 2 minute video to show you how from +JKeet - Teacher Tech Tips
Here's an example of how I've used it in the classroom - Year 8 are learning about development indicators. They first have to interpret the meaning of the images and then categorise them into social and economic indicators. Next they re-arrange the hexagons to show how they are related to underline the complexity of measuring a country's 'development'.
Related posts:
http://invisiblelearning.blogspot.co.uk/2011/04/solo-enquiry.html
http://invisiblelearning.blogspot.co.uk/search/label/flexagons