It is not even a month since I suggested in this column that no teacher went into their classroom thinking they were risking their life. And then last week the unthinkable happened: Ann Maguire, a teacher of Spanish, was stabbed to death at Corpus Christi Catholic College in Leeds.
The grief that her family, friends and colleagues must feel is difficult to imagine. Ms Maguire had taught at the school for 40 years and had been due to retire later this year but her commitment had not waned. According to reports, when she was murdered she had come in on her day off to support her students in their exam preparation.
Tributes have flown in from the people who encountered her both as a teacher and as a human being in her four-decade career in education. Her husband and daughters have described those tributes as a source of great comfort.
It is unclear when, if ever, we will get true clarity about how and why this tragedy happened. Predictably, however, it has led to concerns about teacher and student safety in schools, with Unison Scotland reportedly claiming that there is a "culture of under-reporting" and that the thousands of assaults logged each year are only "the tip of the iceberg".
Larry Flanagan, general secretary of the EIS teaching union, also says there is anecdotal evidence of an increase in the number of serious incidents of violence and intimidation.
Few would like to see metal detectors and high-security gates installed in UK schools. But ways must be found to ensure the safety of staff and students, whether that means an increased presence of "campus cops" or improved dialogue between social services, police, schools and the community. Or perhaps we need other, more innovative approaches.
But as well as lessons on security, this horrendous incident teaches us something completely different too.
Ms Maguire has been described as an unbelievably committed teacher who left her mark on the lives of countless young people. And the way in which these young people have come forward to tell their stories shows just how deep and lasting the impact of one teacher can be.
As David Grevemberg, chief executive of the forthcoming Glasgow 2014 Commonwealth Games, said last week, everyone has a story of an inspirational teacher who touched their life. The My Best Teacher feature that appears in this magazine every week only reinforces this simple fact. Ms Maguire was clearly among the very best of an influential profession.
It is easy to lose sight of as we find ourselves in the middle of exam time, curriculum change and a huge workload. But teachers truly have power, not just to impart knowledge but to change lives, every single day of their careers.