Question: From your work, how much impact can a teacher really make on achievement? (I've recently read 1-14% of progress is due to the teacher, the remainder is genetic/upbringing/etc - is that right?)
I would imagine that any figure for something like this could only really be an estimate (or even a guess?), given the fact that teacher influence will operate as a huge number of tiny effects on multiple variables rather than any one measurable contribution. I think all teachers (certainly in mainstream education settings) quite quickly realise that they are a very small cog in a very large and complex machine, but that this doesn’t make them unimportant!
That said, we can measure other contributions to school outcomes more easily, and they sometimes seem to explain results so well that, as you suggest, there isn’t a huge amount left that can be explained by teacher excellence.
“school and pupil characteristics account for around 85 per cent of the difference between disadvantaged pupils in London and the north. Much of the remaining 15 per cent is because pupils in London are taking more subjects that count in Attainment 8, but this has been closing over recent years.”
This is only trying to explain the differences between the settings (not the effectiveness of the school overall), but it does show that, at most, only a tiny amount of this difference is down to teaching quality.