In the world of education, what are "the three Rs"?

And yet they can't spell.

Yara Modaberi, Well, of course, "writing" is the correct spelling, but, I'm sure most will agree, "the three Rs" isn't just easier and quicker to say, but also sounds much catchier than the ungainly alternative "the Ah(r), Double-yoo, Aye". Besides, all it costs is the silent 'w' and the short 'e' sound. No big deal for a cool mnemonic device AFAIC!