In the words of a recent British Prime Minister: Education Education Education!
There is a vast amount of material available on the web that can be used for educational purposes. If you come across any that you think would be useful to put here please let me know at email@example.com. The following are some examples.
1. The education page of the BCA is under construction and already has some excellent links to educational material. For instance there are some wonderful applets showing how diffraction works etc. 
2. The International Union Of Crystallography has a number of educational links, although some are now missing. 
3. I strongly recommend the following e-crystallography course. It covers a huge range of topics and has some excellent Java applets that can be downloaded. In particular see the applets for making an Escher type pattern, for diffraction geometry and the wonderful charge-flipping applet. In the last one you can draw a molecule or collection of atoms,calculate the diffraction pattern and then allow the charge flipping iteration work back from the intensity data to your original molecule. Magic! 
4. Another set of applets are given in the Interactive Structure Factor tutorial 
5. A Bragg's law applet 
1. Two computer programs that I have made available for free to simulate the motion of monatomic and diatomic chains. The first program is for a 1-dimensional chain and the second for a two-dimensional system (the motions are mind-boggling!). I discovered while writing these programs that there is a diagram showing acoustic and optic mode displacements that appears in almost all solid state textbooks: unfortunately this diagram is incorrect.
2. A free computer program called VIBRATE! to compute the irreducible representations for vibrational modes. Useful especially for Raman spectroscopy. 
1. The Bilbao Crystallographic server is a must for anyone interested in learning about and making use of symmetry. 
2. The online program ISODISTORT is extremely useful if you are interested in phase transitions between group-subgroup related phases of a crystal. It includes an excellent Java applet to display the relevant distortion modes.
3. If you are interested in magnetic symmetry, I recommend consulting the downloadable files produced by Danny Litvin at . You can download a complete set of "International Tables" specific to magnetic space groups.
4.Space group diagrams and details can also be found at .
1. Diffraction geometry. A useful discussion of different diffraction geometries can be found at 
2. Introduction to powder diffraction: 
3. A demonstration of two-slit diffraction 
4. A tutorial on diffraction 
1. Introduction to Rietveld powder refinement. 
2. Neutron Rietveld refinement by Bob von Dreele. Quote: “A Rietveld refinement is never perfected, merely abandoned” (P. Stephens, 2000)
3. An excellent online tutorial on Rietveld refinement including videos. 
--Glazer 16:07, 17 May 2012 (BST)