A level predicted grades

It’s not normal to have a quota of A grades to predict and then no more*

I totally agree, that's why she needs to speak to thr head. But it also needs to be tied to the fact the teacher thinks there is a seventy percent chance the student won't achieve an A*. If you look at that fact in isolation then yes it's right not to predict it.

because it means that the school is then not trusted by the unis

Errr no that really doesn't happen. Admissions tutors have hundred of forms to work through - the idea that they'll look at the school code and remember that one under predicted last year! The predicted grade is taken at face value, along with the knowledge that they'll mostly be inaccurate.

He can apply to Cambridge without an A prediction. GCSE results and results on entrance exams will be far more important than the predicted grade. If he has strong GCSEs he should focus on preparing for the entrance test for his subject and apply anyway. The absence of an A prediction shouldn’t prevent him being interviewed.

Schools do discourage pupils who they think will not achieve the grades

And this is fine. It’s not normal to have a quota of A grades to predict and then no more. ‘Sorry I can’t predict you an A because you haven’t a hope of getting it’ is fine. ‘Sorry, I can’t predict you an A* because I gave the last one to Johnny’ isn’t.

For some totally bizarre and unexplainable reason very few kids go onto med school or oxbridge - because they actively discourage them from applying

This makes absolutely no logical sense. I'm sure you must be able to see that. If this is what the school boasts about why would they discourage capable kids who they think have a shot at it not to apply. In fact, I think you're going further than that, I think you're insinuating they make the predictions so they can't.

It makes no sense. I think you should talk to the head, because with the best will in the world I cannot see how what you're posting is accurate.

Schools do discourage pupils who they think will not achieve the grades and are sure won't get in not to waste their time applying, sure, that's the way it should be, but that is not the same as discouraging kids who would have a shot at it, or trying to set rules to prevent it.

Why would they do that? It serves them no benefit at all.

Is it an academy or a LA maintained school?

Bluntness but you’re assuming that the ‘30%’ and the ‘14%’ have any scientific accuracy behind them. Neither do. The teacher thinks the OP’s DS has a shot at an A. There are reasons to think he will do better next year. If he’s not predicted an A, he can’t apply to Cambridge. If they do predict him an A* and he doesn’t get it then....nothing really for the school, and so long as he has an insurance offer he’ll be fine.
Plenty of other schools will be predicting their bright kids optimistic grades in order to open that first door for them.

Where did this 14% come from?
Why are the school discouraging bright kids from applying to Oxbridge? It’s all very odd.

The only sure way to not get an offer from Cambridge is to not apply, and he has 4 other UCAS choices. Also, they have their own aptitude tests (not sure if this is all subjects?) which I believe they introduced because of AS being essentially scrapped and not wanting to rely solely on grades predicted by schools.

I'm pretty sure they know the outcome of that test before they have to make their UCAS choices (ie if they fluff it they won't waste a choice) so maybe encourage him to sit the test and see how he fares, in a 'nothing ventured, nothing gained' spirit?

That's not quite rhe whole story giraffe, the teacher has said he has only a thirty percent chance of achieving it, that's quite low and clearly as such wouldn't be an accurate prediction, they are saying he's much more likely to get an a.

I'm fairly sure if they thought he had more chance of getting it, he'd be in the 14 percent.

As said, 14 percent predicted a star is always quite high. I think if there was a case for him there rhe school would go over the 14 percent, all schools love to boast of oxbridge applicant success stories, the fact they won't and are saying it's 30 percent indicates they really don't feel a star would be an accurate prediction.

5/6 UCAS predicted grades are wrong, it really isn’t a science, it’s a guesstimate, especially early in Y13 when most predicted grades are set, and now without solid AS results which count towards 50% of the final grade to go on as well.

The teacher isn’t saying that the DS isn’t capable of an A, the teacher is saying that he’s not allowed to predict him a A because of this 14% figure. This means that the DS’s A-level predictions are not based on his performance, but on the A-level predictions of other students.

Perhaps the school will not over predict because it means that the school is then not trusted by the unis when their predictions arrive and it thus disadvantages their whole cohort.

Believe me there is nothing more that a school would like to do than get Oxbridge offers which it can then use in their promotional literature. I am afraid OP you might just have to adjust your expectations of your child and that the school are trying to use the kindest route of saying he may not be performing at the level you hope him to be.

I am unsure why a gap year is not possible? If your DS is going to get the grades you anticipate he can apply next year with the grades and then thumb his nose at the school!

It'd be worth checking if the school feel they give accurate predictions. DD's school told us last November, their predictions are normally very accurate and they won't budge due to parental pressure. DD has her predictions for her uni applications later this year, A*AB, that B is going to restrict what she wants to study and where. She's fighting her case with the school, they've agreed to an exam resit and looking at her work carefully. Resit hasn't gone well, so perhaps a B really is the likely outcome.

Salty I'm not an expert on Cambridge admissions (especially as so much of it is devolved to the colleges) but given that DS's GCSE school is potentially underperforming and that we're talking about a one-grade difference at A-level predictions, I wouldn't assume that not changing the prediction will mean no interview.

Does DS have a preferred college in mind? It might be worth contacting a few admissions tutors (contact info will be on the college websites) and just asking them whether missing the standard offer by one grade at prediction stage would be a complete dealbreaker. Is the underprediction in the subject DS wants to study? What are his GCSE results like?

I think the question here is why he is not one of the 14 percent of students predicted to get an A*. 14 percent is quite a lot.

I think the school would not be being completely honest if they predicted him an A* when they know it's a 70 percent chance he won't achieve that.

I get the frustration you are feeling, but the bigger picture is will he achieve it or not, and sadly at this stage it seems unlikely. If it was 50/50 the case would be stronger.

I would appeal but I think you may find rhe school will stand behind their predictions for him. As an educational establishment they stand to lose reputation and damage students if they become renowned for wasting universities time by erroneous predictions.

However if it was me, I'd still see what I can do for him to get the prediction but I'd also try to understand the schools position.

I’ve never heard of a student switching sixth forms for Y13 (usually they restart Y12) but I would imagine there would be huge issues with finding an alternative who can offer the same options with the same exam boards, and even if you can do that, content may be taught in a different order which could leave gaps in knowledge.
Then you still need predicted grades based on..? The predicted grades of the previous school? And you would need for Cambridge entry, UCAS forms done pretty sharpish and references written by a school that don’t know him at all.

If kids have been kicked out for mock results then you could try to find out what they’re doing?

What kind of school is it @SaltyMyDear? Depending on its performance record at GCSE and A-level, and how many people it usually sends to Oxbridge in a typical year, your DS might be flagged under Cambridge's contextual admissions process.

Also, depending on where you live, his application might get some geodemographic flags. This is all part of Cambridge's efforts to widen their pool of applicants/students and, although they are pretty vague about exactly what this means for individual applications, it should probably mean that missing the standard offer by one grade in predictions won't necessarily mean no interview.

More detail here: I'd encourage you to read it, Cambridge are unusually open about this process!

www.undergraduate.study.cam.ac.uk/applying/contextual-data

It sounds a bit dodgy that they have quotas of grades to give out and that the Oxbridge stream is being discouraged.
Can they not take a holistic view looking at GCSEs etc?

I don't spot in your post he wanted Cambridge.
Is that the only place he will consider?
Depending on the subject some RG unis have courses in clearing which came as a surprise to me.

My attempt at a clicky link https://www.thestudentroom.co.uk/university/apply/adjustment/changing-university-via-adjustment-what-you-need-to-know