I was at a Roundtable discussion this week hosted by CMRE in which Professor Simon Burgess introduced discussions on what we know about teacher effectiveness and the impact that teachers ,both good and bad ,have on student performance and attainment. The discussions were under the Chatham House Rule but my selected key points listed below, made by Burgess, draw on material already published by him and other researchers . (see Notes below )
In short, his research shows that teachers matter a great deal: having a one-standard deviation better teacher raises the test score by (at least) 25% of a standard deviation. Having a good teacher as opposed to a mediocre or poor teacher makes a big difference
Teacher effectiveness matters enormously. A pupil being taught for eight GCSEs by all effective teachers (those at the 75th percentile of the teacher effectiveness distribution) will achieve an overall GCSE score four grades higher than the same pupil being taught for eight GCSEs by all ineffective teachers (at the 25th percentile). A range of studies have consistently shown a very high impact of teacher effectiveness on pupil progress. While there are also papers contesting the validity of the assumptions required to identify true effectiveness, there is other research arguing that the results are secure.
Measures of teacher effectiveness are noisy. Numerous factors affect exam scores, from good or bad luck on exam day, through the pupil’s ability, motivation and background to a school’s resources. Research shows that it is possible to measure a teacher’s contribution to this, but it is an estimate with less-than-perfect precision. There is simple sampling variation, plus non-persistent variation arising from various classroom factors. For example, a teacher’s score is any one year may be affected by being assigned a particularly difficult (or motivated) class (in a way not accounted for in the analysis)
Experience doesn’t help beyond three years. Research shows that on average teachers do become more effective in their first two or three years. Thereafter, there is no evidence of systematic gains as their experience increases: a teacher is as effective after three years as s/he will be after 13 years and 30 years.
Good teachers are hard to spot ex ante. One of the more surprising findings to come out of the research on teacher effectiveness over the last decade has been that the characteristics that one might have thought would be associated with better teachers simply aren’t. Experience, a Masters degree, and a good academic record in general are not correlated with greater effectiveness in the classroom. These results have been found in both the US and England. We need to be careful what we are claiming here. The research shows that easily observable, objective characteristics such as those noted above, variables typically available to researchers, are no use in predicting teacher effectiveness. This is not to say that no-one can identify an effective teacher, nor that more detailed subjective data (for example, from watching a lesson) can be useful. No doubt many Headteachers are adept at spotting teaching talent. But there are enough who aren’t to mean that there are ineffective teachers working in classrooms (even in schools rated outstanding)
Very few teachers (ie bad and mediocre teachers) are dismissed from the profession in England. (Dylan Wiliam has suggested that there are few long term benefits in seeking out poor teachers in order to dismiss them-much better to use your time and resources to identify poor teachers early on and give them the crucial support they need from their better peers to improve their teaching quality)
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