I often talk and write about collective teacher (or rather, team) efficacy. This collective belief that you can make a difference as a team can have a huge impact on learning, but… This becomes difficult when the team is constantly changing. Teacher turnover is rarely good for a school. When teachers leave, experience is lost too. We have seen before that high staff turnover can go hand in hand with lower learning outcomes. But does this apply to all staff members in the same way? And what does staff turnover mean specifically for students with disabilities?
A new study by Lindsey Kaler, Roddy Theobald, Nathan Jones, and Elizabeth Bettini tries to answer these questions. The researchers distinguish between general education teachers, special education teachers, and teaching assistants. Note that special education teachers do not necessarily work in separate special education schools. They also look separately at students with and without disabilities.
The researchers used administrative data from the US state of Washington from 2009 to 2019. They linked staff turnover data to growth in maths and language scores among students with and without an Individualised Education Program (IEP).
Staff turnover was quite high during this period. On average, about 14 per cent of general education teachers left each year, compared with 21 per cent of special education teachers. Among teaching assistants, the percentages were even higher: approximately 19% and 25%, respectively.
The departure of general education teachers matters in particular
Of all forms of staff turnover examined, turnover among general education teachers was most consistently associated with lower growth in test scores. This was the case for students both with and without disabilities.
Fortunately, the effect sizes are relatively small. If one in five general education teachers were to leave, the drop in learning gains is estimated to be quite small. So the effects are definitely not dramatic in this case. However, the researchers consistently find that higher turnover is associated with lower gains. This is also true for students with disabilities. For special education teachers, the pattern is more specific: their turnover seems to matter particularly for students with disabilities.
For teaching assistants, the researchers did not find any statistically significant negative impact on growth in language or maths scores. It should be noted that the absence of statistically significant negative impacts does not mean that their stability is irrelevant. For instance, their work may influence behaviour, attendance, and goal achievement, among others.
Is this causal?
The authors themselves speak, rather remarkably, of causal effects. And they do quite a lot to support this claim. They follow schools over several years, compare schools primarily with themselves over time, and account for changing school characteristics.
Still, I would be more cautious, but you know me by now. It remains observational research. It would be wrong to completely rule out the possibility that changes within a school cause both higher staff turnover and poorer student outcomes.
Inclusion also means shared responsibility
When thinking about students with disabilities, we often focus on specialists in the first place. This study suggests that the stability of this group matters. But the turnover of general education teachers appears to be equally, if not more, important. In fact, this is the most consistent pattern in the results.