Two new studies paint a divergent picture of whether teachers unions contribute to better schools.

One finds that states with stronger unions saw more of the money earmarked for education actually reach classrooms, which in turn helps student learning.

Another shows that weakening unions in Wisconsin led to increases in the share of college students training to be teachers, potentially reducing teacher shortages.

Together, they’re a glimpse into the debate about the effects of teachers unions on schools, one where research offers few definitive conclusions. And they come at a moment when teacher groups are ascendant politically — flexing their political muscle in the form of strikes and walkouts across the country and drawing support from Democratic candidates for president.

“Unions — it’s complicated, because they’re not just the oppositional force that a lot of people want to paint them but they’re not only the champions of education and learning that they might portray themselves to be,” said Matt Kraft, an education researcher at Brown University.

Stronger unions mean more money for schools, and more student learning

Between 1990 and 2011, dozens of states reworked their formulas for funding schools. In many cases, the goal was to send more money to schools in high-poverty districts that had historically been shortchanged.

But extra dollars don’t reach schools automatically. Some localities receiving more money from the state decided simply to replace some of their local spending with the new state money.

A new study shows that didn’t happen much in states with strong unions. There, all or most of the state money earmarked for schools got spent on schools. In places with weak unions, many of the extra dollars for schools were used to cut local property taxes instead.

The study finds that in strong union states, much of the new money went into higher salaries for teachers. And that in turn led to benefits for students. In states with strong unions, state funding changes led to bigger test score improvements.

The results bolster an argument long advanced by teachers unions: that by advocating for their members, they’re also doing good for students. And it replicates prior research showing that school funding increases benefit students.

“The bottom line is that the actions of these teacher unions was in line with the ideas of the courts when they forced school finance reforms: i.e. to increase spending in poor districts and help students in those districts,” said Eric Brunner, one of the researchers and a professor at the University of Connecticut.

‘War on teachers’ not deterring would-be teachers in Wisconsin

Meanwhile, a Wisconsin study looked at the impact of a law that decimated teachers unions, and found that it didn’t stop college students from wanting to go into education.

Researcher Jason Baron compared trends in teaching degrees earned in Wisconsin after 2011’s Act 10 to those trends in nearby states. The Wisconsin law appeared to lead to a 20 percent increase in the share of college students training to become a teacher, relative to other states, a boost entirely driven by students at the state’s most selective universities.

The results surprised Baron, whose previous research suggested that Act 10 led to declines in student test scores.

“Even though Act 10 had negative, disruptive effects on student achievement in the short run, the present study suggests that the reform may have led to an increase in the quality of prospective teachers in the state,” Baron writes.

Officials in Wisconsin might also be surprised by these findings because the overall number of  teaching degrees earned in the state has fallen, in line with national trends. What Baron shows is that interest in teaching was dropping pre-Act 10 and fell faster in other states than in Wisconsin.

Why would that be? One explanation is simple: salaries for novice teachers in the state have been rising. After Act 10, a number of districts adopted incentive pay policies or stopped using salary schedules based on years of experience.

“The potential for higher starting wages created a strong incentive for students to enter the teacher workforce even though Act 10 substantially undercut job security,” Kraft said.

A separate study has shown that teachers in Wisconsin are responding to performance pay, with better teachers migrating to districts that have it. But this also may be exacerbating inequities among schools, because more affluent districts were slightly more likely to adopt merit pay systems.

Baron says the study still leaves a number of questions unanswered, including what the lasting effects of the law on students will be.

“An analysis of the long-run effects that arise after Act 10’s initial shock remains to be done,” Baron wrote.