Experts have been sounding alarms for years about cracks in Michigan’s teacher pipeline, pointing out that fewer people are entering teacher training programs and becoming certified as educators. Headlines periodically warn of a “teacher shortage.”

“Teacher turnover is only part of the teacher supply chain equation,” said Jack Elsey, executive director of the Detroit Children’s Fund, a nonprofit. “The percentage of teachers who are enrolling in teacher prep, the number of people going into teaching — all of those metrics scare the pants off me.”

Ask many observers how to reduce teacher turnover, and they will tell you that turnover is merely a symptom of a much larger problem.

Simply put, the state isn’t investing enough in schools, said Barbara Schneider, a sociologist at Michigan State University who has studied turnover.

“It’s a resource issue,” she said.

Efforts to reduce turnover in Michigan have often centered on simply giving teachers more money for their work. When a nonprofit in Detroit pumped millions of dollars into a handful of higher performing charter schools, some of the money went toward retention bonuses. Just last year, the state set aside $5 million for a similar program: new teachers will receive as much as $1,000 for staying on after their first year, with the possibility of receiving more if they stay on for three years.

But these programs are small in the context of Michigan’s $15 billion annual education budget.

David Hecker, president of the American Federation of Teachers Michigan, credited Gov. Gretchen Whitmer with pushing the program through, saying it communicates to teachers that they are valued. But he said the amount of money in the program “isn’t going to change anyone’s life.”

By contrast, the amount of money Michigan spends on schools has dropped sharply — it declined 30 percent, adjusting for inflation, between 2002 and 2015 as state revenue for schools was reduced by tax cuts.

There has been only one comprehensive effort to estimate the cost of adequately educating Michigan’s roughly 1.5 million students. Experts say the state falls more about $3.6 billion short of that mark.

Schneider says increased funding wouldn’t just allow for increased teacher pay, but also for increased funding for schools so that they could pay for improvements that would improve working conditions at schools. More money could pay for decreased class sizes, better teacher training, better learning materials, or for more school staff — paraprofessionals, counselors, and social workers — who give teachers the freedom to focus on teaching.

“Apart from really systematic investment in schools, it’s going to be hard to improve working conditions meaningfully,” said Lucy Sorensen, a professor at the State University of New York Albany who has studied teacher turnover. “To the extent that urban schools are less funded, higher stress work environments serving students with greater needs, that’s more likely to cause teachers to depart.”