I recall, during 1959/60, attending a lecture on, and demonstration of, the properties of liquefied gases in one of the labs. I can't recall who the teacher was or whether this was during normal lesson times or immediately after school. I do recall sitting on one of those high stool things (buffets to give them their correct name) next to Dave Pamment. The lecture culminated in the teacher immersing various objects in a container of liquid nitrogen (I believe). One such item was a rubber which was then struck with a small hammer, the shrapnel flying everywhere. Dave picked up a bit and stuck it in his pocket. The piece de resistance was an egg, cracked into the container and similarly smashed. Dave immediately picked up the largest piece and stuck it in his pocket as a keepsake. We were dismissed and as we were making our way to the bus Dave put his hand into his pocket to retrieve his booty. It had, by now, returned to ambient temperature provoking foul expletives from Dave and general hilarity from the rest of us. I'm sure that the teacher thought that such a vivid demonstration would ensure it was the physical principals outlined that would stay with us for the rest of our lives rather than the picture of an eggy blazer.
People worry about mercury in their dental fillings. I seem to remember spending most of my GenSci classes with Ben Tren not listening to a word he was saying but rather concentrating on prising fom the cracks in the chemi lab workbenches the bits of mercury that had accumulated. You then made them into as big a ball of mercury as possible before smashing it to bits again and watching the bits hide again in the workbench cracks.