Clear boards?

Factual Questions
#1

Having grown up around, beside–and occasionally inside–televisions, I’ve seen my share of movies and commercials, many of which happen to deal with math. Whenever I catch the season’s hottest differentiating flick (“difs”), however, I have invariably found the following scenario played out: a slightly eccentric professor is standing in front of the class scrawling miles of equations… ON A CLEAR BOARD. A CLEAR BOARD! A CLEAR…ahhh, you get it. This is driving me crazy. No one has been able to provide a satisfactory response to the following questions:

  • What is this clear material?
  • What does one use to write on it? (e.g. dry-erase markers, grease pencil, mascara…)
  • Why does it have to be clear? Are there any distinct advantages a transparent board has over a white board or the classic chalkboard?
  • Is this board actually used outside of Hollywood? If so, why is it exclusive to science and mathematics instructors?
  • …and… uh… what is the cost of this material, say, per sq. foot? Or panel. Whatever they sell these things by… (cubits?)

I’m losing weight. I can’t sleep at night. My friends and family say I’m starting to withdraw.

Please advise.

#2

This was actually discussed recently, in reference to Good Will Hunting, IIRC. You could try doing a search, but I’m pretty sure the consensus was that grease pencil is probably the best for writing on glass. Dry erase also works relatively well on glass.

#3

The only purpose of using a clear board is for the viewer. It allows the actor to write (backwards) without obstructing the camera’s view of the text. Also, it looks cool.

#4

In addition to grease pencils and dry-erase pens, there are pens designed specifically for writing on glass; in my favourite movie, Amelie, the (delicious) Audrey Tatou uses one to write a daily menu on a glass partition in the café-tabac where she(or rather, her titular character) works.

In movies, as friedo suggests, the main use seems to be that we can see the character face-on, at the same time as seeing what he/she is writing.