Condemnation of the topic of "inscriptions on the fence - naphig need and how to explain it to children?"

- My husband in childhood wrote on the fence about the teacher of German "Ivan Petrovich - a fool!"
I don’t eat for FIU.
So, 25 years have passed... The fence is in place, and the inscription is constantly UPDATE!!! Current students...
With his husband, the teacher was young, now it is about retirement, but nothing has changed in his character.
How to explain this to children - I don't know, but this is an ancient version of the VKontakte wall... As they say, who agrees - put likes or paint...