We often talk about “the teacher shortage” as if it were a single problem with a single cause and a straightforward solution. But as soon as you look more closely, that picture starts to crumble. In fact, a proper teacher shortage analysis reveals a much more complex reality. A recent international study based on twenty years of PIRLS data makes this very clear, focusing specifically on shortages of teachers specialised in reading. As so often in education research, the real story is not in the average, but in the differences.

The researchers led by Gratia O’Rafferty analysed five PIRLS cycles between 2001 and 2021 across 65 education systems. School principals were asked whether a shortage of reading specialists affected their school’s capacity to provide instruction. The answers ranged from “not at all” to “a lot”. That is a subjective measure, but precisely for that reason, it is informative. This is not about vacancy statistics on paper, but about experienced constraints in daily practice.

At first glance, the international picture seems almost reassuring. On average, the proportion of schools reporting a shortage of reading teachers remained fairly stable over the past two decades. There is no dramatic global upward trend. But that average hides enormous variation. Some countries report persistently high shortages year after year. Others consistently report low levels. And several show volatile patterns, with shortages rising, falling, and rising again.

The United States and the Netherlands stand out for their strong increases over time. In the United States, roughly one-third of schools reported a shortage in 2001. By 2021, that figure had risen to well over two-thirds. The Netherlands follows a similar trajectory. At the same time, there are countries where the problem has become markedly smaller. Bulgaria is the clearest example. There, the share of schools reporting a shortage of reading specialists dropped by more than forty percentage points. That change coincided with targeted reforms in teacher education following EU accession.

The first conclusion is hard to avoid. Teacher shortages are not a natural phenomenon. They are highly sensitive to policy.

A second question concerns distribution. Where are shortages most acute? Are they concentrated in schools serving more disadvantaged students? Do rural schools suffer more than urban ones? Here, the picture becomes more complex and more interesting.

Across all countries, differences between low- and high-socioeconomic-status schools are smaller than many would expect. In the statistical analyses, socioeconomic status explains only a very small share of the overall variation. That does not mean inequality is irrelevant. It means that its role differs sharply between countries.

In some systems, shortages are clearly more prevalent in schools with many disadvantaged students. In others, the opposite pattern appears. Sweden is a striking example. In several measurement cycles, more advantaged schools reported shortages more often than schools serving lower socioeconomic populations. That pattern aligns with a policy tradition that explicitly compensates schools in more challenging contexts through additional resources and financial incentives. In contrast, in the United States, shortages are consistently more common in low-socioeconomic-status schools. That pattern fits well with concerns about social reproduction. Students who already face disadvantages are also more likely to be taught by less experienced or less specialised teachers.

Geography tells a similar story. On average, differences between urban and rural schools are modest and stable. But within individual countries, the balance shifts over time. In some years, rural schools struggle more. In others, shortages are more pronounced in large urban schools with high turnover and demanding working conditions. The idea that location alone explains teacher shortages does not hold up.

So what explains most of the variation? The answer is clear. Countries do. Or more precisely, national contexts do. Between 60 and 70 per cent of the variation in reported shortages occurs at the country level. Changes over time, school socioeconomic composition, or geographic location explain far less.

That immediately shifts the focus to structural choices. How attractive countries make the teaching profession. How they organise teacher education. What career paths do they offer? How teachers experience workload, status, and professional support. These system-level conditions shape shortages far more than labels such as urban or rural, advantaged or disadvantaged.

This makes international comparison both frustrating and hopeful. Frustrating, because no single model can simply be copied elsewhere. Hopeful, because it sfor hows that policy choices matter. Systems that invest in high-quality teacher education, support early-career teachers, and compensate demanding working conditions manage shortages better, or at least distribute them more fairly.

One point deserves particular emphasis. This study does not examine teachers in general. It focuses on teachers specialised in reading. That distinction is crucial. If reading forms the foundation for all further learning, then who has access to that expertise is not a marginal issue. It sits at the heart of educational quality and equity.

The problem, then, is not only whether there are enough teachers. It is also where teachers end up, how they are trained, and under what conditions they stay. Approaches that reduce the teacher shortage to slogans or single-issue solutions fail to capture that reality.

Twenty years of data lead to a simple conclusion. Teacher shortages do not arise overnight. They emerge from long-term policy choices. And those choices can, in fact, be made differently.