The sentence:
Teachers are increasingly conscious of what they refer to as the hidden curriculum, a reference to the less formal influences exerted by a school on the pupils' behavior and attitudes to such things as rule conformity, punishment, tolerance, and social responsibility.
I myself know what "formal" above means, but I cannot explain it in other words (especially in Japanese to my students). Could anybody paraphrase it (in English, of course) ?
Hello again Taka

Would it be easier to approach the meaning via the full phrase, i.e. 'less
formal influences'?

If so...I would say that 'formal' here = 'relating to rules and customs'.

So 'less formal influences' I would interpret as meaning 'influences other than
school rules, traditions, customs, codes of conduct, etc'.

If teachers unofficially hinted to pupils that respect for school rules was rather
an outdated idea, you could say that 'less formal influences' were being
'exerted...on the pupils'...attitudes to...rule conformity'.

But as you say, it's easier to understand than explain. Maybe someone else
would like to have a go.

I see. Thank you, MrP!