We use an infrared camera to look at objects of different temperatures (ice, hot water, candle flame). We then look at objects made of different materials (acrylic, plastic trash bag, aluminum plate) to see which ones are transparent in the infrared vs the visible part of the spectrum. Finally, liquid nitrogen is poured over a cup of hot water.

The camera we use is a FLIR E-95, which can detect wavelengths in the 7.5-14 micron range. Never attempt to drink liquid nitrogen!