4 Polarised light - stress polarisation on plastics

I am going to change the order of the studio lighting exercises. On Thursday I learnt that some students had difficulty getting their 120 film processed and printed in time for the deadline last year. This is probably because of the unusual (professional) film format and the moves towards digital printing.
We will shoot the polarised images as soon as practicable to enable printing by the deadline.
If you are in the studio group you can bring in small clear objects to construct a picture on the lightbox. The brief says plastics for safety reasons but polarisors can also have an effect on glass.

If you find this request confusing don't worry it should clarify once we have seen the demonstration!!