Schoolchildren in this country are currently mired in SATs. These are tests designed to assess how well a school (not individual children) is doing, but have been being roundly criticised because they're stupid and pointless. Michael Rosen in particular has been very vocal on Twitter about the SPaG (spelling, punctuation and grammar) one, which I believe is happening today.
It does seem a stupid test, and many of the examples he has picked out do contain confusing or apparently pointless things. The main criticism many people seem to have is that young children don't need to know this stuff, that it's too hard, and that it doesn't take creativity or expression into account, and that grammar puts kids off language. This facebook post is (I think) an analogy which makes exactly that point - that focussing too much on the mechanics ruins the fun of it. Lynne Murphy has written a good post pointing out that learning grammar is good and useful and helps you to know more about language. I would go further, though, and make the case that grammar is absolutely bloody brilliant.
Spelling and punctuation are a bit dull. The types of grammar that kids are having to learn is a bit dull: they're essentially labelling parts of speech. But real grammar, the kind that I spend all day every day thinking about, the grammar that I chose to study for 8 years and then make my career, is fantastically and endlessly interesting.
How can you not be fascinated by the fact that words might not really exist, that adjectives occur in a particular order (small green apples, not green small apples), that the rules of be deletion in AAVE are precisely the same as the rules of be contraction in British English, that you can have a cheeky Nando's but not a cheeky salad, that speakers can innovate constructions like because noun and the exact same damn thing happens in Finnish and French and who knows what other languages, that through reanalysis and tiny shifts Latin became the romance languages, that languages all over the world are wonderfully diverse but equally astonishingly similar... hell, even the most basic fact about syntax, that it is a hierarchically-structured system, is still amazing to me and something that most people don't even realise.
And even more than this, most of what I've just said is controversial to some people. We don't know the answers. Language, and I take grammar to be central to language (some would disagree but I'm happy to be biased), is inextricably bound up with our humanity and we don't even know how it works. We are still finding out. Isn't that exciting?
Don't teach 8-year-olds about subordinating conjunctions. It probably will put them off writing stories for fun. And don't ban 'slang'. That'll make them scared to speak. Once again, I make my call for all teachers to study linguistics and then teach everyone grammar - but fun grammar. Learn a foreign language and see how it's like English, or different from English, and wonder why. Look at Beowulf and Chaucer and marvel at how far English has come, and what happened to that verb-second word order. And then come and study linguistics.