I did A level biology; it was a class of 22 (I vaguely remember), 19 XX, 2 XY and one that we weren't entirely sure about.
I missed a couple of important lessons for personal reasons, so was trying to catch up. I was sat at one of the benches in the lab, with a rat in advanced stage of dissection, my note pad, a sandwich, a Mars bar and a cup of tea.
I was quite happily poking around the squishy bits, occasionally slurping tea, masticating bread or munching on the choccy, then adding to the diagram I was creating illustrating the various bits I'd seen. I'd also started preparing some slides of some of the cells ready to be stained for microscope work.
The teacher was known as Bio Bill (Mr Williams); and he was brilliant. He approached me and asked if I would put the food away and concentrate on the work at hand. When I looked puzzled, he pointed out all of my classmates standing outside of the room, puking up!