The National Curriculum asks primary school children in England to learn that there are four types of sentence: statement, question, command and exclamation. They are tested on this at the ages of 7 and 11.
Examples that are given are things like:
I am a good dog.
Are you a good dog?
Be a good dog!
What a good dog you are!
It doesn't take long for any of us to look at signs, ads, poems, songs, book and film titles, newspaper headlines, film scripts, plays, instructions and of course in the whole 'unpoliced' world of texts, digital media, websites, sub-titles etc, to see that the very word 'sentence' is not as simple as it sounds. Out there, in the real world there are examples of writing beginning with a capital letter and ending with a full stop: single words, phrases without verbs, lists and so on. So in fact there aren't just four types of sentence. There are many types of sentence. What's more there are many examples of the first kind of sentence that children see in public that won't have a full stop at the end - in particular with signs and ads.
The main reason why the National Curriculum classification of sentences exists is that it's based on how grammarians a long time ago classified Latin sentences. The Latin they looked at was mostly the formal written prose and poetry of the educated elite. If you reduce language to one tiny part of its total output, you can of course make up abstract rules and classifications like this, much more easily than if you look at a language as a whole - 'in use', as we say, including of course how we speak to each other.
So here we are with these four types of sentence. First thing to say is that the terms themselves - statement, question, command and exclamation are not grammatical terms. They are descriptions based on meaning or what is known as 'semantic' terms. Yet, the 'defining' characteristic of these terms is grammatical - that's to say, each of them is based on a 'verb form'. That is, a form the verb is in in the sentence.
With the statement, you can see that the 'verb form' is: 'I am'. In a question, it's 'Are you..' With a command, it's 'Be...' and with the exclamation it's 'What' + 'you are'.
Each of these verb forms has a technical name. They are the sole reason for dividing up the language into these four different categories, but as I said, the descriptions are 'semantic' not 'grammatical'. There is a contradiction here: anyone reading this can think of statements, questions, commands and exclamations that do not use these same 'verb forms'. Give it a try:
'Yes' and 'No' are often statements. We can ask questions when we speak through intonation which when we're writing we can indicate with a question mark. 'She was happy?' This is a totally legitimate and way of writing a piece of dialogue or a bit of internal thought in a story. Notice though, the 'verb form' is that of a statement ('She was...'). Now do commands. Yes, of course we can use that 'verb form' to command: 'Do this, do that!' but of course we can use that 'verb form' to not really command as in 'Stay well' or 'Have a nice time'. And we can command using other structures as with 'You must go out now.' Or 'No smoking'. As for exclamations, it's absurd to restrict our exclaiming to permitted structures - as with 'what a...' We exclaim in many ways through intonation and by marking this in writing with an exclamation mark. Great that we can!
There is therefore a mismatch between the terms used to classify sentences and the grammatical form that is really being used to do the classifying. What's more, the very act of classifying sentences into only four types is absurd.
How have we got to a point where this kind of stuff is foisted onto children as if it's good linguistics, or good grammar or makes any kind of sense?
The route is from the attempt by grammarians to classify the sentences they saw when they read Latin. They justified the categories by working backwards from the verb forms as with 'imperative verb form = command'. This had an internal logic to it. Every time they saw the 'imperative' it was a command. All commands in front of them in the Latin texts they saw (or wanted to talk about) were commands. Watertight, self-referential way of working.
Then grammarians of English simply took these terms and plonked them on to English. In simple examples - as with the ones I gave at the beginning about the dog - it works. This is what we might call 'ideal language' in the way that Boyle invented Boyle's Law talking about 'ideal gases'. Real gases don't behave 100% according to Boyle's Law. Real language doesn't behave 100% according to this 'ideal' classification of sentences.
Then along came Gove. Gove asked Lord Bew to do a report on Assessment and Accountability. Bew produced an interim report. I read it. It was actually a fair analysis of the pros and cons of different ways of assessing pupils and making schools accountable - though all in the context of the appalling league-table and punitive Ofsted set-up. Gove looked at it and said that he wanted a form of assessment that measured how teachers teach. The Bew Report committee - none of whom were linguists or grammarians - decided that they needed a simple measuring system, one that tested children on 'right and wrong answers'. Someone said, 'Grammar!' Now here's where the problem comes in. If you think of grammar as an honest, thorough and as-scientific-as-possible way of describing 'uses - and users - of language' then there is no way that 'grammar' can give you right and wrong answers. (I once asked a grammarian to give me the grammar for 'It wasn't to be', a phrase that the England football manager had used. He spent half a page trying to and in the end gave up. This was the same grammarian who advised the government on grammar!
So, in order to achieve their right/wrong formula, Gove asked for a particular kind of grammar - what turned out to be SPaG and later, GPS. In fact, he became so hands-on about this, to my knowledge, he made special demands for at least one item that he thought should be included. Gove is not a linguist. Gove is not a grammarian.
Turn that on its head: the grammarians they hired were not school teachers, were not teacher educators, were not educationalists.
That's how and why we arrived at a point at which we tell children there are four types of sentence (wrong) and the four types are: statement, question, command and exclamation, based on 'verb forms' even though there are 100s of examples where statements, questions, commands and exclamations can be made without using those four 'verb forms'.
Education, England, 2021.