Kindergarten, first grade, and second grade are often free of the high-stakes testing common in later grades — but those years are still high-stakes for students’ learning and development.

That means it’s a big problem when schools encourage their least effective teachers to work with their youngest students. And a new study says that the pressure of school accountability systems may be encouraging exactly that.

“Evidence on the importance of early-grades learning for later life outcomes suggests that a system that pushes schools to concentrate ineffective teachers in the earliest grades could have serious unintended consequences,” write study authors Jason Grissom of Vanderbilt and Demetra Kalogrides and Susanna Loeb of Stanford.

The research comes at an opportune time. All 50 states are in the middle of crafting new systems designed to hold schools accountable for student learning. And this is just the latest study to point out just how much those systems matter — for good and for ill.

The study, published earlier this month in the peer-reviewed American Educational Research Journal, focuses on Miami-Dade County schools, the fourth-largest district in the country, from 2003 to 2014. Florida had strict accountability rules during that period, including performance-based letter grades for schools. (Those policies have been promoted as a national model by former Florida Governor Jeb Bush and his national education reform outfit, where Education Secretary Betsy DeVos previously served on the board.)

The trio of researchers hypothesized that because Florida focuses on the performance of students in certain grades and subjects — generally third through 10th grade math and English — less-effective teachers would get shunted to other assignments, like early elementary grades or social studies.

That’s exactly what they found.

In particular, elementary teachers effective at raising test scores tended to end up teaching grades 3-6, while lower-performing ones moved toward early grades.

While that may have helped schools look better, it didn’t help students. Indeed, the study finds that being assigned a teacher in early elementary school who switched from a higher grade led to reduced academic achievement, effects that persisted through at least third grade.

The impact was modest in size, akin to being assigned a novice teacher as opposed to a more experienced one.

The study is limited in that it focuses on just a single district, albeit a very large one — a point the authors acknowledge. Still, the results are consistent with past research in North Carolina and Florida as a whole, and district leaders elsewhere have acknowledged responding to test pressure in the same way.

“There was once upon a time that, when the test was only grades 3 through 12, we put the least effective teachers in K-2,” schools chief Sharon Griffin of Shelby County schools in Memphis said earlier this year. “We can’t do that anymore. We’re killing third grade and then we have students who get in third grade whose challenges are so great, they never ever catch up.”

While the Florida study can’t definitively link the migration of teachers to the state’s accountability system, evidence suggests that it was a contributing factor.

For one, the pattern is more pronounced in F-rated schools, which face the greatest pressure to raise test scores. The pattern is also stronger when principals have more control over staffing decisions — consistent with the idea that school leaders are moving teachers around with accountability systems in mind.

Previous research of policies like No Child Left Behind that threaten to sanction schools with low test scores have found both benefits and downsides. On the positive side, accountability can lead to higher achievement on low-stakes exams and improved instruction; studies of Florida’s system, in particular, have found a number of positive effects. On the negative side, high-stakes testing has caused cheating, teaching to the test, and suspensions of students unlikely to test well.

So how can districts avoid the unintended consequences for young students documented by the Miami-Dade study?

One idea is to emphasize student proficiency in third grade, a proxy for how well schools have taught kids in kindergarten, first and second grades.

Scholars generally say that focusing on progress from year to year is a better gauge of school effectiveness than student proficiency. But a heavily growth-based system could actually give schools an incentive to lower student achievement in early grades.

“These results do make an argument for weighting [proficiency] in those early tests to essentially guard against totally ignoring those early grades,” said Grissom, who also noted that states could make more efforts to directly measure performance of the youngest students.

But Morgan Polikoff, an associate professor at the University of Southern California, was more skeptical of this approach.

“It’s not as if states are going to add grades K-2 testing, so schools and districts will always have this incentive (or think they do),” he told Chalkbeat in an email. “I think measurement is always going to be an issue in those early grades.”