Polarisation
Was doing polarisation with my class and unusualy for me I did a couple of real demos rather than simulated ones. First I did a demo passing a laser through some sugar solution placed between crosses polaroids. Not exremely convincing, would have been better to put the solution into a glass cube rather than a beaker. The other demo was looking at a piece of perspex through a polaroid filter, the perspex was held in front of my computer screen to provide polarised light. Students liked this one as you can see. They liked the hologram of a dog even more, pity this isn't on the syllabus.