I do recall in primary school we were doing some weird experiment thing with cows eyeballs. It was the last day of term before the six week holidays.
The classroom was in an annexe and presumably the cleaner locked up and that was that for the summer.
September, we all stood outside, teacher put key in annexe door and ushered us all in, we all came back out rather quickly. Cows eyeballs had been left in margarine tubs on the side for the entire summer. We had lessons in the hall for several days 😂