This pack links to the Materials area of Launchpad and illustrates the amazing colours that appear when water freezing is viewed through special filters.

Contents include:
• 2 squares of polarising film • 1 petri dish

• This pack contains special filters that enable you to see things that are normally invisible.

• When water turns into ice, it looks clear but in fact it can alter light in strange ways so that it appears coloured if looked at through the filters.

• Many other things such as crumpled cellophane appear coloured through the filters, and this effect is used by engineers to pinpoint the position of stresses in objects.