Teacher shortages are not a new concern and the subject areas with the biggest gaps remain fairly consistent. Still, as the 2017-2018 school year was beginning, CNN had an extensive report on the challenge. Among the findings:

The Learning Policy Institute estimated that if trends continue, there could be a nationwide shortfall of 112,000 teachers by 2018.

Public schools in 48 states and the District of Columbia report teacher shortages in math for the 2017-18 school year, according to the U.S. Department of Education. Forty-six states report shortages in special education, 43 in science and 41 in foreign languages.

Nationwide, teacher education enrollments dropped 35% between 2009 and 2014, the most recent year for which data are available, according to the Learning Policy Institute.

A survey at UCLA found that freshmen’s interest in teaching as a career has steadily declined over the past decade.

Dan Goldhaber, director of the University of Washington’s Center for Education Data and Research, who studies educational trends at the University of Washington, sees two main reasons.

Math and science teachers aren’t paid enough. Salaries for U.S. secondary school teachers have largely remained the same over the past two decades, according to the National Center for Education Statistics.

And students in the STEM fields (science, technology, engineering and math) can make more in other professions than they would teaching.

Teaching in the U.S. is too demanding. About 8% of teachers leave teaching each year, with two-thirds quitting before retirement, according to the Learning Policy Institute. This is double the percentage of teachers leaving the profession in countries like Singapore and Finland.

As far as potential solutions:

• Help students be more strategic about their teaching opportunities. When students enter teaching certification programs, let them know where the jobs are. In many parts of the country, they’ll have an easier time finding jobs to teach math or science than English.
• Partner school districts with local college and university programs. Though the teacher shortage is rooted partly in subject areas, it’s also a matter of location. Schools in low-income areas struggle more to fill positions. “It is the kids that are oftentimes most at risk that are the ones who are likely to suffer the most,” Goldhaber said.

One way to fix that would be to pull in students from local higher-ed programs to help teach in those areas. Many may stick around for a full-time job after graduation.

• Make teacher certification national instead of state by state.Prospective teachers must pass an exam specific to the state they want to work in. But if a teacher wants to move from, say, Pennsylvania to California, they can’t immediately apply for jobs there. By having a national certification exam, teachers would have more mobility to go where they’re needed.