The hover tag on the recent xkcd cartoon Misconceptions mentions the common glass mistake, that it is a slow moving fluid (also seen: supercooled fluid). I remarked to a colleague that part of the foundation for that was not understanding that there is a glass transition, while the more common observation is a first-order phase transition from liquid to solid. He mentioned a good example of a glass transition:
Take a cold piece of chewing gum. Break it in half. That’s a material in the glassy state.
Put the gum in your mouth and wait a short time. Then bite. Elastic and rubbery, but still a solid. Somewhere in that temperature span is the glass transition,
It’s even worse than that. Take a four foot length of 7 mm Pyrex tubing and horizontally support it near its ends, as by placing it on two pegs separated by 3 feet. Over a period of months (weight the center for faster action) there will obtain a lovely vertically bowed deflection downward. Remove the glass tubing and it will remain curved.
Place it on its side in a furnace and slowly increase the temperature. Before it reaches its strain point of 510 C it will have spontaneously straightened.