For this activity you need two polarisers. Simply take a pair of Polaroid sun glasses and break them in two. I"m joking of course, but if you have already broken the glasses you got for viewing 3D films then you might as well chuck "em. They are circular polarisers - not the same as plane polarisation.Your computer screen gives out polarised light so you can use that as polariser 1, the second polariser will be your...