Concerning the processing speed and ability
Of course ability plays a role in outcomes, but not as an explanation for 35%. I'll come to this later. But processing speed is not the central issue of cognitive ability.
Noble, your photo of memo from JCQ about access arrangements talks about Cognitive processing, not processing speed. By "cognitive processing" they mean cognitive ability, which is analysed in finer detail for various components / factors of it. Processing speed is one of the factors, it is on the list, but not the central one by far. This is a question for EP and cognitive scientists, but generally, working memory tends to be the most limiting / most predictive factor of cognitive ability, not processing speed. Most cognitive assessment batteries do not even include processing speed, it is done on demand where there is a suspicion if could be a factor. This is why I said it is niche, but of course important for individuals concerned. Other factors in cognitive ability are verbal and non verbal reasoning. A child with spiky cognitive profile with strong reasoning, average working memory and weakness in processing speed may do very well, the processing speed will not necessarily be the defining factor, but of course they would be disadvantaged by tuition 'at speed'. With SEN every child is an individual this is why I don't want to focus on processing speed. There is a range of factors encapsulated in a broader term of cognitive ability, and then there are specific things like SpLd, Dyslexia, ASD, Dispraxia, Cerebral Palsy... I take the point from Alexander that her DC has 24%-tile processing speed in addition to a range of other factors including ASD. Of course it is a factor for her DC. My DCs also have ASD, spiky profiles with significant problems, but processing speed is not one of them. In itself it does not make my DC any less or more able than Alexander's. I don't know what role processing speed plays in Moderate Learning Difficulties, but still, I suppose it could be referred to as ability for the purpose of this discussion. MLD are diagnosed for 2%-tile.
To be clear JCQ extra time, according to this memo, is given following a difficult process by Senco, to children with presumed SEN, when at least two of their cognitive scores are 'low average', not sure whether they mean below 25%-tile, it would be specific to the test.
On a broader point that weakness in cognitive processing requires extra time during tuition. The answer requires to disambiguate the muddle. First, what you label as weakness, second what is the policy of dealing with the weakness if it is labelled, third, what happens with 35% and sets.
- What is labeled as weakness? MLD is 2.2%-tile.
Low ability is 10%-tile, IQ of 70-79,as I posted earlier. They are expected to struggle.
Low average ability is 10 to 25%-tile. They are expected to keep up with some difficulty. 25 to 75%-tile are average.
About 15% of children have some SEN, many among them would have high cognitive ability. SEN are not necessarily bottom ability.
So where do you draw the line, Noble? Roughly which ability is too low for GCSEs?
You can't just leave it open and elastic, to extend every time as it suits.
- Policy.
Are less able actually given extra time? No. They stay in education the same time as the most able, but they exit without good qualifications. Their curriculum is cut short because of slower progress (as I understand Nobles's point ). Only children with SEN, those with EHCPs are enabled to continue until the age of 25.
It is not acknowledged in policy that lower sets need extra time.
At least half of students in lower sets would not meet any definition of SEN and would not qualify for extra time. The policy does not provide for time. Perhaps this is the problem that needs to be acknowledged.
It is also not acknowledged transparently in the public discourse that lower sets are not expected to pass GCSEs due to system set-up, that they will never have the time to cover the curriculum, because the time is only just enough for the most able.
- the 35%
Since you talk of cognitive processing weaknesses, JCQ state that extra time is given if at least two measures are 'low average'. If you take 'low average' as a guidance threshold of GCSE pass ability, i am not sure all students in lower sets would have low-average scores. Definitely not all students missing on GCSEs are low average. 'Low average' percentiles are between 10 and 25%- tile.
So actually 10% within the 35% who fail GCSE (35 take away 25 = 10) would not fit in this definition of those that need extra time... the JCQ definition of weakness.
There is no ability based reasonable explanation why those with ability between 25 and 35%-tile don't get good GCSEs.
And given that qualifications are equivalent internationally, you absolutely can compare with success rates in other countries.
The Finns, the French, northern Europe, but also Estonia, Poland etc have no trouble educating those with 25-35%-tile ability to the equivalent of A-level.
So the explanation purely based on low ability, on the premise that the children are not good enough does not stand really. That could only apply to bottom 10%.
The explanation is in how the system treats those students.
Others have pointed out that speed of cognitive processing affects pace of learning, and this is not caused by setting.
Speed of learning lays on a bell curve. 'Speed' of teaching is a policy choice. The policy of sets really means the pace of progress for good GCSE is set by top sets since Reception. It progressively amplifies and entrenches the gap between sets and limits curriculum. Thus it puts the lower sets beyond the threshold for GCSE .
Sets is a centrifuge, not a pipeline. Too many get ejected outside the threshold.
Unless you provide extra years of study to the mid and lower ability students, only a truly mixed ability comprehensive class would enable the low average student to just manage within the threshold for good GCSE. Bigger proportion of the cohort would stay within the threshold, go through the same curriculum, while the spread of exam results would reflect variation in ability. The most able will be on top, they have nothing to loose.
In most other countries the assumption is that difference between pace of learning is relatively minor, the whole bell curve of ability can fit within one classroom, and enables to educate the whole cohort with the exception of 5 or 10% in at the same mixed ability pace to the outcome which is equivalent in level to UK.