If I had foreseen the difficulty this question would cause, I would have approached it differently – possibly in the lesson with that grammar point, and certainly when adapting the question from the question bank to the final exam. The grammar point was modal verbs and the question was:
Rewrite the sentences using the modal verbs might, could, might not (mightn’t), or could not (couldn’t).
The first three sentences were:
It is possible that she will come.
It is possible that she won’t come.
It is impossible that he is sick.
The expected/‘correct’ answers are ‘She could/might come’, ‘She might not/mightn’t come’ and ‘He couldn’t come’. (The last is problematic in my idiolect, but I’ll let that pass right now.) The textbook had introduced these modal verbs in terms of possibility and impossibility, but hadn’t provided any examples or exercises exactly like this. As the students in the first class were doing the exam, I wandered around peeking at their progress and answers, and it became clear that they were struggling with this one. I said to them several times, ‘Change the sentence completely. Don’t use “possible” or “impossible”’ and wrote ‘I might be tired’ and ‘I might go to Seoul’ on the board. For fairness, I said and wrote the same in the second class.
In spite of my attempt at help, only three students in the two classes got all three correct, and several more got one or two correct (and maybe the other(s) partly correct). (Had they already learned this transformation, did they understand it from my class despite me not explicitly teaching it, or did they understand my attempt at help?) The others produced 21, 22 and 23 variations on ‘incorrect’ respectively, ranging from ‘She could be come’ and ‘She might might not come’ through to simply rewriting the given sentence or not attempting the question at all. The most common score was zero. Several students wholly or partly crossed out what they had originally written then wrote again, sometimes correctly, sometimes incorrectly again.
The easiest thing to do would have been to mark those 28 incorrect and get on with the rest of it, but the questions arose: ‘Which students fundamentally understand the grammar point and would (or could possibly) communicate in a real-life second-language context?’ and ‘What can I learn from this so as to better teach it the next time round?’. There’s no doubt in my mind that the students who wrote ‘She could be come’ and ‘She might might not come’ do fundamentally understand, could possibly communicate and deserve half a mark. (Half marks make things more complicated for me, but I’m prepared to do it.)
Taking a closer look at just the first sentence (the second and third have ‘not’, which introduces another layer of complexity) the two ‘correct’ answers are ‘She could come’ and ‘She might come’. ‘She could be come’ and ‘She might be come’ got half a mark, but ‘She couldn’t be come’ got nothing for changing the meaning. Some students retained something of the original structure. ‘It might be that she might come’ sounds strange but is otherwise grammatical and communicative. ‘It might that she will come’ and ‘It could that she will come’, omit verb [be], which happens in many contexts in many varieties of English, but not, as far as I know, this one. (The omission of verb [be] by itself rarely affects the meaning.) ‘It could is that she will come’ is only one verb inflection away from being correct, but I had drilled ‘modal plus base verb’.
Most students retained ‘possible’ despite my attempt at help, so I had to give them no mark even for an otherwise correct answer. One used a double modal: ‘It is possible that she might will come’. I’m aware that double modals are fully grammatical in some varieties of English, but they aren’t in standard English. Others replaced ‘will’ with another modal. ‘It is possible that she might come’ is acceptable in real life, but ‘It is possible that she couldn’t come’ changes the meaning. Yet others retained ‘will’ in the second half of the sentence and added another modal verb in the first half. ‘It might be possible that she will come’ is acceptable in real life, but no marks in this exam, while ‘It mightn’t be possible that she will come’ makes my brain hurt (‘It might be possible that that she won’t come’ is more natural – indeed one student wrote that for the second question). ‘It could possible that she will come’ is possibly communicative in real life, but ‘It could not possible that she will come’ changes the meaning (if it means anything at all). The last two variations – ‘It is could possible that she will come’ and ‘It is could that she will come’ – are just possibly communicative in real life, but get no marks in an exam.
As I was marking these, I encountered them in random order, and they seemed – well – random, but when I started analysing them, definite patterns emerged. The question then is, ‘How did the students produce these not-standard-but-not-quite-random patterns?’. No textbook includes them, no teacher has modelled them, and from what I know of Korean, there’s no first language interference.
So, what could I do the next time around? Firstly, not choose this grammar point for the exam. Secondly, choose different questions to test it. Thirdly, if there’s time, create an extra worksheet for that lesson, focusing on this transformation. Fourthly, provide the first word of the answer – It is possible that she will come > She ________________. Fifthly, rewrite the question – perhaps ‘Q Will Eun-ju come to the party tonight? A I don’t know. She ________ come’ (which is almost too easy).
Another question in the same set was ‘It is possible it will rain later’, which is made more difficult by the dummy pronoun ‘it’. One student wrote ‘Rain might later’, which is a very good attempt – it’s got a subject, a verb and extra information, and can only mean ‘It might rain later’. (Indeed, ‘Might rain later’ is a perfect informal version in many varieties o English). I remember one night in Australia, when my wife looked at the clouds and said ‘Rain will soon’.