To see how big the difference was, (Hanushek, 2006) took a group of 50 teachers. They found that students taught by the most effective teacher in that group of 50 teachers learn in six months what those taught by the average teacher learn in a year. On the other hand students taught by the least effective teacher in that group of 50 teachers will take two years to achieve the same learning.
Another study around this time showed that in the classrooms of the most effective teachers students from disadvantaged backgrounds learn at the same rate as those from advantaged backgrounds, while students with behavioral difficulties learn at the same rate as those without behavioral difficulties (Hamre & Pianta, 2005).
According to Dylan Wiliam (2011)
The most powerful teacher knowledge is not explicit
- That’s why telling teachers what to do doesn’t work
- What we know is more than we can say
- And that is why professional development is not on it’s own, effective
Improving practice involves changing habits, not adding knowledge
- That’s why it’s hard
- And the hardest bit is not getting new ideas into people’s heads
- It’s getting the old ones out
- That’s why it takes time
But it doesn’t happen naturally
- If it did, the most experienced teachers would be the most productive, and that’s not true (Hanushek, 2005)
Hargraves and Fullan (2012) define to the quality of teaching, and the quality of the teachers as professional capital. They refer to research that shows the US teacher judgement systems that concentrate on removing those at the bottom and rewarding those at the top hasn’t shifted the overall quality of teaching.
It seems we can make judgements on teachers, but that doesn’t necessarily improve teaching.
So how do we go about improving this professional capital when teaching is recognised as being unforgivingly complex?