The Broken Equation: When Labor Interests and Student Learning Come Apart

The San Francisco teachers strike, Wisconsin’s Act 10, and arguing better about teachers unions | Charting the Course

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The question: When teachers unions fight to preserve institutional structures like seniority-based pay, does that actually serve students — or can labor interests and student learning come apart?

The backdrop: The United Educators of San Francisco struck for four days in February 2025, framing the strike as pro-student. Critics called it self-serving. Neither side engaged with the strongest available evidence.

The evidence: Three studies on Wisconsin’s Act 10 paint a complicated picture. Baron (2018) found short-run declines in student achievement after union power was reduced. Biasi (2021) and Biasi & Sandholtz (2025) found that districts replacing rigid union pay schedules with flexible ones saw long-run gains of 0.15–0.21 standard deviations — with the largest gains for disadvantaged students. Foy (forthcoming) found the same positive effects using a different method entirely.

The caveats: These are findings from one state with unusually rigid pay schedules. Flexible pay also widened the gender wage gap. The broader literature on unions and achievement is mixed. Short-run disruptions were real and shouldn’t be dismissed.

The problem: Union advocates pushing to repeal Act 10 aren’t engaging with this research at all. Neither are most critics of the UESF strike, who rely on accusations of bad faith rather than evidence about institutional design.

The bottom line: The equation “supporting unions = supporting teachers = supporting students” has a broken link. That doesn’t mean unions should be abolished — but it does mean they can’t be exempt from scrutiny on student outcomes, especially when the evidence cuts against the structures they’re fighting to preserve.

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The strike last week by the United Educators of San Francisco was historic — the first in nearly half a century. Yet the back-and-forth spurred by the strike was nothing if not familiar. When the teachers union and its supporters claim that they strike on behalf of the students, critical parents and observers respond that it’s not about the children’s interests at all — only the union’s own interests.

In the UESF’s strike announcement on Monday, February 9th, the pro-student framing was front and center: “the growing vacancy and turnover crisis in SFUSD harms students every single day.” The argument was implicit but straightforward. Students need stability; stability means retaining good teachers; and retaining good teachers means higher wages and competitive benefits. Educators will leave if they can’t afford housing in the city or healthcare for their families, and the more who leave, the more those who stay become overloaded and under-resourced. None of this advances student learning. “We will return to our classrooms,” the strikers assure the reader, “the moment the District agrees to the conditions that stabilize our schools and protect the education our students deserve.”

The critics, in turn, claimed this framing was belied by their conduct, which appeared to aim less at stability than at leverage. Even if the worst anecdotes were misunderstandings or outliers, several well-established actions smacked of bad faith. An independent fact-finding report noted that the union “has not met its burden of proof” that the district could afford its demands. It also called UESF’s combined wage-and-benefits proposal “simply not an option,” and recommended “a conservative approach” to “survive State scrutiny.” The union rejected those findings and struck anyway. It declined Mayor Daniel Lurie’s and Speaker Emerita Nancy Pelosi’s calls for a three-day delay so schools could remain open during continued negotiations. At 10 p.m. on the second night of the strike, the district had a new health care counter ready but the union left the table without reviewing it.

To union critics, a striking teacher’s sign that asked whether the rain was “Maria Su’s crocodile tears pretending she cares about our kids“ was rich with irony — couldn’t the same be charged of the union?

Now that the dust has settled, we must wait to see whether the $183 million deal can get past state fiscal advisers or proceed without layoffs. But the public commentary on the strike raises important questions about how we argue about teachers unions. When cash-strapped parents are suddenly forced to arrange for childcare, it’s easy to understand how ‘You don’t really care about students’ becomes a reflexive reaction. But it’s a rare thing for attributions of cynical motives to advance debate. Vanishingly few teachers enter the profession without caring for the well-being of their students. Most want what is best for students, and, to that extent, a teachers union must also ultimately represent what is best for students, so long as it faithfully represents what teachers want. It seems unlikely that UESF believes its tactics were, overall, bad for students but good for the union; more likely, they just sincerely believe that what’s good for the union is also good for the students.

If their goal is not just voicing frustration but successfully changing minds, critics of UESF should set intentions aside and focus on a more specific question: Do the institutional structures that teachers unions fight to preserve actually serve the students? Naturally, the union thinks the answer is yes. But what if the evidence is more complicated?

Act 10 & its Legacy

The most provocative data about the effects of teachers unions, for me, comes from studies on the impact of Wisconsin’s Act 10. Act 10 deserves some background. Passed in 2011 — when I was still attending high school in Green Bay, WI — Act 10 was unveiled by Governor Scott Walker as a “budget repair bill” aimed at addressing the state deficit; this would be achieved primarily by reducing compensation to public-sector employees. As a product of a progressive family that included multiple government employees, I was enraged. For us, supporting unions was supporting the working class; and
supporting teachers unions was supporting teachers, and supporting teachers was supporting students. The equation was uncomplicated.

That this battle was happening in Wisconsin made it feel especially significant. In 1959, Wisconsin became the first state to grant public employees the right to collectively bargain — a landmark in American labor history. Act 10 was a seismic reversal of that legacy. An existential threat to public-sector unions, the law limited collective bargaining to base wages capped at inflation, required teachers to contribute to their own pensions and healthcare, mandated annual union recertification elections, and prohibited automatic dues collection. More than 100,000 people protested in the Capitol. Fourteen Democratic state senators fled to Illinois to deny the quorum needed for a vote. A recall effort gathered more than 900,000 signatures.

I was angry at being a year too young to vote in that recall election; when the results came in, I was livid. Walker won by a larger margin than he did in his original election; after everyone saw how he’d treated public employees, how could he have even more support?

I carried a settled view of Act 10 for years: the unions and their supporters were right, Walker was wrong, and future data would confirm it. If you’d told me in 2011 that the law would be struck down fourteen years later — as it now has been, in October 2024, I would have predicted being thrilled. Recently, however, things got more complicated.

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Act 10 offered something of a natural experiment for social scientists. While the law imposed strict limits on collective bargaining agreements, it did not cancel existing ones. Pre-existing CBAs remained in force until they expired, and since expiration dates varied across different Wisconsin school districts, some districts were exposed to the reforms immediately while exposure in others was delayed by months or years. Researchers could compare outcomes across districts with different exposure timings, controlling for the kinds of confounding factors that usually plague evaluations of public policy.

The first notable study exploiting this variation looked like a vindication for teachers unions. In 2018, economist E. Jason Baron found that “the reduction in union power associated with Act 10 reduced composite scores on the state’s standardized exam … by roughly 20% of a standard deviation” — a meaningful decline, and one concentrated in the lower half of the achievement distribution. The explanation appeared straightforward: the law triggered a sharp increase in teacher turnover and a reduction in salaries, both of which had disruptive effects on student achievement.

While Baron’s working paper was quickly cited by union-supportive outlets as evidence for the harms of Act 10, in it he stresses that its findings should be treated as “purely short-run” and “future research” is still necessary:

Importantly, because the identification strategy is structured so that the estimated treatment effects are immediate to the decline in unionization, the findings presented in this study should be interpreted as purely short-run and likely as a transitional effect from an old steady state to a new equilibrium. While I provide evidence that Act 10 had negative, disruptive effects on student achievement, I leave it to future research to fully characterize Wisconsin’s post-Act 10 long-run equilibrium. Nevertheless, declines in test scores, even in the short run, could have lasting effects on students.

Future research into the law’s disruptions did, in fact, complicate the picture considerably. In 2021, Yale economist Barbara Biasi published a (celebrated!) paper arguing that the Wisconsin school districts that replaced the rigid, seniority-based pay schedules that unions had negotiated with more flexible pay schedules in the wake of Act 10 attracted higher-performing teachers, as measured by their value-added contributions to student test score growth; lower-performing teachers, meanwhile, “either mov[ed] to districts which remained with the salary schedules or le[ft] the public school system altogether. As a result,” Biasi concludes, “the composition of the teaching workforce improved in FP districts. Effort exerted by all teachers also increased and, subsequently, test scores improved.

In 2025 follow-up, Biasi and co-author Wayne Sandholtz extended the analysis to five years post-implementation and to students grade 3–8, a broader and younger population than the high schoolers in Baron (2018). The results inverted Baron’s findings: after five years, average student test scores increased by 0.15–0.17 standard deviations, and by 0.21 for economically disadvantaged students.

Now, it is important to frame the contrast between these studies carefully. Baron (2018) captured a real transitional disruption: teachers left, schools were destabilized, and students struggled to adjust. However, what Biasi (2021) and Biasi & Sandholtz (2025) capture is also real: when the dust settled, Wisconsin students in the districts that had replaced union-backed pay schedules saw long-run gains — especially the disadvantaged.

Further evidence that Act 10 benefited student achievement comes from a current working paper by economist Morgan Foy, who used a different identification strategy entirely — union decertification elections rather than CBA expiration dates — and found the same positive achievement effects. Foy’s most provocative finding was about the mechanism, which in fact competes with the explanations offered by Biasi (2021) and Biasi & Sandholtz (2025): the gains appeared to come not primarily from replacing low-performing teachers with high-performing ones, but from increased productivity among the very same teachers. Foy also found lower-performing teachers were more likely to be union members. This is, to put it mildly, an uncomfortable finding for uncritical union supporters.

Some Caveats

Let me acknowledge what this evidence does not show. These are findings about one reform in one state; Wisconsin had a particular labor-market, a particular demographic profile, and had unusually rigid seniority-based pay schedules before Act 10. The broader academic literature on unions and student achievement is genuinely mixed. It would be too rash to generalize from Wisconsin to nationwide claims about the effects of weakening teachers unions on student learning.

Moreover, Biasi’s own work shows that, in addition to bringing higher test scores, flexible pay reforms also exacerbate a gender wage gap, mainly attributable to women being less likely to negotiate aggressively when offered a position. Notwithstanding its dampening effects on student achievement, collective bargaining served a pay equity function that it no longer can after Act 10. Flexible pay reforms also present a double-edged sword: although performance improves for disadvantaged students in the districts that attract high-performing teachers, some disadvantaged students in the districts they leave may lose out. Baron’s caution, too, remains a live concern: the students whose scores fall in the short term may still suffer lasting effects.

We cannot, then, characterize the impacts of Act 10 in Wisconsin schools in any tidy way. Just as it is unproductive to criticize teachers unions on the basis of alleged unsavory intentions, so is it too hasty to claim that these studies show unambiguously “good” or “bad” outcomes for student learning. But we simply will not make progress in our debates about teachers unions if we continue to ignore the findings that show negative effects on student achievement. Teachers unions will not reckon with the most robust studies until their critics start to rely on them.

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In December 2024, a WI circuit judge ruled that by exempting all public-safety workers except teachers and other municipal employees from state restrictions on collective bargaining, major sections of Act 10 violated the state’s equal protection doctrine. Although a higher court stayed the ruling, union voices have celebrated the development. Yet absent from these statements is any engagement with the complications introduced by recent research. Studies have moved forward; advocate talking points have not.

Some critics of the Act 10 repeal efforts offer breakdowns of the resulting costs to school districts. But the costs that should concern education advocates aren’t just fiscal. They include the potential reversal of gains in student achievement — gains that were largest for the students who can least afford to lose them.

Progressives cannot credibly advocate for repealing Act 10 without at least acknowledging that there is strong evidence that it improved student achievement. Especially insofar as progressives remain committed to equity, they must also grapple with the finding that these benefits were largest for the most disadvantaged students. If you care about educational equity, you have to grapple with this. You may grapple with it and still conclude that restoring collective bargaining is the right call — that the distributional risks, the gender equity costs, the value of institutional worker voice, and the limitations of generalizing from one state outweigh the measured gains. That is a defensible position. But it is not the position the repeal coalition is taking. They are simply not engaging with the evidence at all.

That insight is valuable. But it also doesn’t resolve the deeper structural question for San Francisco and its public schools: even if the pension crisis were solved tomorrow, would union-negotiated pay schedules — the kind that reward seniority over effectiveness and protect lower-performing teachers from accountability — actually serve students? The evidence from Wisconsin suggests the answer is more complicated than anyone on that picket line wants to hear. Demanding that union policies do not harm student learning is not ipso facto anti- teacher; it is at least as “pro-student” as promoting stability in schools. The equation I grew up with — “supporting unions = supporting teachers = supporting students” — has a broken link. Supporting teachers and supporting students are not always the same thing, and the institutional structures of collective bargaining can drive a wedge between them.

I don’t wish for unions to be abolished, and I don’t believe that union leaders are all Evrart Claires. Unions provide educators real benefits, many of which may be justified independently from any instrumental relationship to student test scores. But those benefits do not exempt unions from scrutiny on student outcomes. And when unions resist the kind of pay flexibility that rigorous research shows improves learning — particularly for disadvantaged kids — they need to explain why, in terms that go beyond “worker dignity” and “the right to bargain.”

Whatever union structure ultimately prevails — in Wisconsin, in San Francisco, or anywhere else — it must not backtrack on the achievement gains the evidence has documented. If the price of restoring collective bargaining is reimposing rigid seniority schedules that drive effective teachers away and shield ineffective ones from accountability, then we are choosing adult interests over children’s learning. And if we do that while claiming it’s “all for the kids,” we should not be surprised when parents stop believing us.

The evidence is strong enough that I can no longer maintain the uncomplicated equation I grew up with. But it is also not strong enough to support the mirror-image certainty that unions are simply bad for kids. What it demands — of anyone who takes student learning seriously — is that we stop treating this as a settled question with tribal answers, and start treating it as what it actually is: a genuinely difficult problem, where the interests of workers and the interests of children can come apart, and where honest people have to decide what to prioritize when they do.