There were a number of requests for extra credit possibilities. Here is a small project that will contribute to my teaching the class better in the future. It involves making a crystal form model out of posterboard, like those we have in class made of wood. Each model can earn up to 25 points of extra credit, and you can do as many as two. These points will be added to your course score before curving.

Details:

• Models should be about 10-12 inches long when complete
• Use heavy posterboard, or balsa wood, and tape. It should be durable enough to last for years of use.
• Each form should be a single color (you can use differently colored posterboard, or you can paint/color it after assembling), and different forms should be different colors. So, a cube would be a single color, while a tetragonal prism would have two colors, one for the four sides of the prism itself, and one for the pinacoid that forms the top and bottom (if you hold it so the A₄ rotation axis is vertical).
• The models must be accurate and precise - if there is supposed to be a particular symmetry, then it should really look like it has that symmetry.
• You need to sign up for a particular form - you can't choose your own (I'd get 50 cubes!). I will give you a small wooden model that you can work from to help you.
• You should also turn in a short (half-page or so) write-up, giving the following for your model:
  • Crystal System
  • A sketch of the model with the location of the crystal axes included, and correctly labeled.
  • For each form, the name of the form, the Miller indices of each face in the form (do not write this on the model itself), and the form symbol
• If you wish to do one of these, see me after class, or send me email.

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