"Strange times are these in which we live when old and young are taught falsehoods in school. And the person that dares to tell the truth is called at once a lunatic and fool."
Again, alarm bells go off in my head. It's some years since university, but I did read a fair bit of Plato in those days, and something doesn't quite sound very Platonic about this quote. That is, while I'm sure Plato would have agreed with the observation that falsehoods are taught, it seems a little out of character for him to describe it as "strange"; I sort of get the impression that he took it for granted that there were and perhaps always would be people authoritatively professing nonsense.
I mean, the character of Socrates is absolutely central to almost all of Plato's dialogues, and the whole story of Socrates (the historical figure as well as Plato's version) is all about how rare and subversive genuine wisdom is. Famously, Socrates was said by the Oracle to be the wisest of men, which Socrates could only explain as meaning that while all men were ignorant, all but Socrates were unaware even of their own ignorance. Throughout Plato's writing, it never seems as if he thinks his moment in history is peculiar in this regard, that most people are ignorant and think themselves wise. So it would be surprising indeed for Plato to describe this state of affairs as "strange times".
Another suspicious stylistic detail: the lines rhyme. They don't scan particularly well, so it doesn't come across as verse, but the writing is a little bit stilted, as if the author took pains to end with "school" and "fool". The construction "at once a lunatic and fool" is contrived versification. Plato's dialogues (at least in translation) always come across as a much more natural, conversational style, with more regard for precision of meaning rather than poetic beauty.
So I searched for the phrase directly on Google. Lots of hits, just blandly crediting Plato, but (also suspiciously) never mentioning which work it was taken from. That in itself is suspicious; one would expect that if it was actually from Plato, somebody might have cited chapter and verse, but no.
I've just searched through all of the Platonic dialogues on Project Gutenberg, without success. The phrase "strange times" doesn't seem to occur at all, and no instance of "school" turns up anything remotely like the alleged quote. I'm therefore pretty confident when I say that this quote isn't actually from Plato. Dunno who it is from, but it ain't Plato.