I remember we were doing something experiments with electricity and the teacher asked some question. I just answered that it’s a stream of negatively charged particles.

The concept of electrons or charged particles wasn’t introduced yet. So this didn’t make sense to students who learned according to the teacher's plan. I think he wanted us to develop an idea of charge ourselves instead of learning from a book.

(I think this is an outdated way of teaching because students have so much other resources on the internet to learn from.)