Should I push my CAT4 138 DD to SPGS open day?

I haven’t read the full thread, but I’m not clear what is meant by a “rule-bound atmosphere”. In our experience, Westminster, much like SPGS, is rooted in a liberal educational ethos, and their approach to learning feels quite the opposite to rules? (Other than Westminsters wearing uniforms)

My view on the greater depth and breadth comes from seeing both schools from the inside — the content covered, how the pupils are made to go beyond the curriculum, the enrichment and the number of times our daughter has asked her younger brother things like, “Why are you learning that in this subject?”, “Why is your school making you do(learn) that?” or “We never had to do that in Year X.” If you ask her, she would say his school goes off-piste from the curriculum all the time and does “weird” things. I suspect they arrive at similar outcomes, but by quite different routes.

Personally - if your girl likes STEM - (non-medical) - i’d seriously consider Westminster.
Tiffin is skewed by the medical track, so it’ll be more biology, chemistry, and less maths focused.

And the main benefit of what Westminster does is in the Y7-11 - extending, going deeper and broader, etc.
If you only switch in Six Form - those years are gone and kids have just 1year to focus kn the A-levels/building up UCAS profile, etc.
The kids who’ve been at WUS would have had years of better teaching that your DD would have missed, and it cant be replicated.

A STEM focused girl would be absolutely fine with boys at WUS from 11+.

20ish girls this year 2026, but more next year. There are no siblings policy so boys coming from Westminster Under have to sit 11+ and apply to other schools in case they don’t get offer at Senior. So friends with boys there are now applying to other schools and sitting their 11+.
It would be tougher to get girls into sixth form if there are already girls cohort in that year since less space available.

Westminster is going fully coed and this year girls applying at 11+ so maybe would suit your STEM focus DD.

I’d echo this. I have a daughter at SPGS and a son at Westminster (Great School), and the depth and breadth of the curriculum in STEM (and I would argue in the humanities too to a lesser degree), feel quite different.

That said, I wouldn’t consider either school worth the financial strain if fees are a stretch and you have a place at Tiffin.

This is very funny.

That link is not methodology and does not explain how they define "ability" (there are different concepts around) but you do you.

@WW3
I was more referring to the fact that for a high performing child - Marhs/FM would not be the same workload as two distinct A-levels. There is a lot of overlap. So they can (and should) take another subject that will broaden their Uni options.

Many degrees do count them as 2, and actually require both to be taken, BUT
Medicine, Dentistry, Veterinary Med - DO NOT count them as two (as too similar) - and require Chemistry and/or Biology or Physics

Also - some highly competitive non-mathematical courses at top unis also don’t count them - they’ll state they want 3 A-levels in different subjects.

GCSE are not easier, my DS did both and said iGCSE just had a slightly different structure.

Both GCSE and iGCSE are relatively easy as PP said.

There are quite a few incorrect assumptions in your post but a discussion on psychometrics is a very technical one, and moreover cannot be done without access to the methodology. GL does not publish its methodology so you cannot actually say "CAT4 measures developed ability" as their underlying concepts and theoretical framework are simply not published in detail.

I wouldn't base any decisions on any tests btw. The fact that you put her score in the title shows you put a lot of weight on this number. You didn't say "my STEM focused DD", you specified her score. Human beings, however, are much more complex creations and cannot be defined by numbers.

Actually I can see it’s on the final page!

SPGS don’t seem to differentiate between 9s and 8s in their published results so how do you know they get nearly 100% 9s in English?

The point is that there is no way Godolphin is choosing to do an exam in which they think their students will find it harder to get the top grade.

Also, there is no school in the country, whether private or state, that's going to actively choose an exam in which they think their students will get worse outcomes.

Honestly, I don't think there is as much of a difference between GCSE and iGCSE as people seem to think and I don't think either is particularly easier. Sometimes slightly different content is covered. If you look at the specs of the boards involved they seem to cover very similar things. I would imagine the difference in percentages of 9s is largely down to how selective various schools are.

Cambridge iGCSE has optional
coursework. My DC did the exam only curriculum for both English Lit and Lang.
English Language is notorious for its bizarre marking so wouldn’t read too much into it anyway.