What is among the first actions that brutal totalitarian regimes take upon assuming power? They imprison, exile or “disappear” teachers.

Dictators employ such harsh tactics because of the role teachers play in society. Teachers provide not only a crucial link to our cultural past but also exercise critical influence on the present and the future. Teachers train future citizens on how to think and creatively challenge accepted wisdom, which can threaten the power of tyrants.

But before we rush to congratulate ourselves on how well teachers are treated in our free society, we need to recognize the multiple ways in which damage has been caused to the profession.

The United Nations Educational, Scientific, and Cultural Organization (UNESCO) established World Teachers’ Day – celebrated every year on October 5 since 1994 – as a result of concerns about the historically low status of teachers and their mistreatment.

As a researcher who studies the history of schooling in the United States, I can testify that Americans have long had a deep and enduring ambivalence about teachers: we value their work, but we pay them less respect and less money than those in many other comparable professions. There are plenty of signs that teaching as a vocation is in trouble in the US.

The problem of teacher turnover

Look at how enrollments in teacher preparation programs have plummeted in the last few years in US schools.

The hardest-hit state – California – experienced a 53% decline between 2008 and 2013. Other states are not too far behind – Michigan, for instance, experienced a 38% drop, and Texas a 19% reduction, during the same period.

Several high-profile educators have either decided to “hang up their chalk” or encouraged others to avoid the profession altogether.

And what is causing good, experienced educators to flee the ship of teaching?

Teacher turnover has long been an area of concern (teachers depart at a higher rate than comparable professions). The more precise reasons for recent departures are under scrutiny, but we can point to a variety of likely causes.

First, teachers have experienced heavy attacks from a number of directions over the past 15 years.

Ever since the passage of the No Child Left Behind Act (NCLB) in 2001, which accelerated an ongoing education accountability movement, teachers and schools have felt under immense pressure to improve the annual yearly progress of their students on statewide standardized tests and demonstrate that they are “highly qualified.”

Researchers who investigated these concerns found that teachers generally applaud efforts to improve academic standards, instruction and teacher qualifications. But many of these policies have had profound unintended consequences.

For example, because of the differences between state policies, teachers and schools in one state can be punished for student achievement scores that in other states would be rewarded.

Second, the accountability movement has led many policymakers, especially those keen on finding ways to measure the worth of all things, to fasten onto “value-added measures” (VAM) as a way of evaluating teacher performance.

The idea behind VAM is that yearly student test scores can be used not only to track student achievement but also as a way to measure the instructional impact of their teachers.

Dealing with tests and fixing poverty

On the face of it, such instructional assessments might seem like a reasonable approach. But there are many pitfalls to using a test originally designed to measure students to evaluate teachers.

So much so that eminent scholars in the field of statistics, economics, psychology and education have issued urgent warnings to policymakers that VAM are far too flawed to be of any value in teacher assessment.

Despite such caution, many states have moved forward with the implementation of evaluation systems that employ VAM as a primary mechanism for teacher evaluation, a development that is sure to signal to many teachers that they are in what one researcher calls “a very disempowered line of work” because they have so little control over their professional lives.

Finally, and perhaps most importantly, for decades teachers and schools have been asked to do something that is beyond their control: fix poverty.

While teachers can have profoundly powerful and positive impacts on students, there is an overwhelming amount of research demonstrating that student performance on standardized tests is largely determined by their socioeconomic background.

For a variety of reasons that researchers are still struggling to understand, the achievement scores of students from poor communities across the country are lower than their wealthier counterparts.

Vocation is in trouble

Until we better understand the mechanisms behind the relationship between poverty and achievement, state leaders should be morally bound to avoid legislation or regulations that can “mis-measure” the value of their teachers.

If we want to encourage smart, creative, passionate individuals to enter the teaching ranks, we must insist that they receive the respect, autonomy and intellectual freedom they deserve.

We cannot afford to lose a whole generation of teachers. We will endanger the crucial professional and institutional knowledge that one generation of teachers passes on to another.