Secondary teachers are more likely to run out out of steam than their primary colleagues, government-sponsored research shows.
The study, commissioned by the Department for Education and Skills, identified six professional phases for teachers according to the number of years in the job.
Differences in culture between primaries and secondaries were found to affect teachers' capacity to stay committed to the job at two separate stages of their careers.
"Whereas 85 per cent of primary teachers with eight to 15 years' experience were sustaining their engagement, only 63 per cent of secondary teachers were doing so," said the researchers from Nottingham university and London university's institute of education.
"Conversely, 37 per cent of secondary teachers had a sense of detached engagement, as against 15 per cent of primary teachers (with eight to 15 years' experience)."
They also found differences between primaries and secondaries for teachers with 24-30 years' experience. While 60 per cent of primary teachers in this phase were seen to have retained a strong sense of motivation, more than half of secondary teachers were found to have lost their drive, the research says.
On-the-job training could be a factor: the study found that continuing professional development had a positive impact on all teachers. But while 80 per cent of primary teachers said they were offered enough training, only two-thirds of secondary teachers said the same.
Only 60 per cent of secondary teachers were satisfied with their CPD, compared with three-quarters of primary teachers. Pupil behaviour may also account for the cultural differences between phases. Nearly two-thirds of secondary teachers said behaviour was an issue that sometimes hindered their teaching, compared with 51 per cent of primary staff.
The research was based on interviews conducted between 2001 and 2005 with primary and secondary teachers in seven urban and rural education authorities. Other data included pupil interviews and schools' value-added scores in national tests.
The six career phases were:
* 0-3 years: "a high phase of commitment". Support of school and department leaders was seen as crucial in this period. Poor pupil behaviour had a negative impact.
* 4-7 years: "increased confidence about being effective teachers".
Seventy-eight per cent had taken on extra responsibilities, which boosted their professional identity. Heavy workloads upset some.
* 8-15 years: "managing changes in role and identity: growing tensions and transitions". This phase was seen as a watershed in professional development; 80 per cent had posts of responsibility and many faced decisions about their future careers.
* 16-23 years: "work-life tensions: challenges to motivation and commitment". As well as managing heavy workloads, many faced other demands outside school, making work-life balance a concern. There was a feeling of career stagnation linked to a lack of support in school and negative perceptions of pupil behaviour.
* 24-30 years: "challenges to sustaining motivation". In this phase, teachers struggled to stay motivated in the face of unwelcome policies and initiatives. Pupil behaviour was the main problem for these teachers.
* 31-plus years: "sustainingdeclining motivation, coping with change, looking to retire". For most teachers, this was a phase of high commitment based on positive teacher-pupil relationships and pupil progress.
Government policy, health issues and behaviour were the most negative factors for this group.
Variations in teachers' work, lives and effectiveness is available at: http:www.dfes.gov.ukresearchdatauploadfilesRR743.pdf