Nobody thought it important to consider that teacher preparation programs had for years been graduating twice as many teachers as are needed. According to findings from the American Institutes for Research, over the past 30 years, programs graduated between 175,000 and 300,000 teachers each year, yet consistently school districts have hired only between 60,000 to 140,000 newly minted teachers. Instead, school districts have been far more likely to hire people who already have some teaching experience. Federal data from 1999 to 2012 show that only about 30 percent of districts’ new hires were straight out of a teacher prep program.There's more:
For 30 years, most districts in the nation have struggled to find enough certified secondary science and math teachers. And rural and urban districts have been unable to tap into a reliable and stable source of new teachers.With a free market in education : there would be no shortages.
One answer to the problem is to pay such teachers more than others, but most districts continue to reject that solution because it is untenable with unions. We also could ramp up the availability of part-time positions for science, technology, engineering and math (STEM) teachers, but — again — few schools and states embrace this option because unions worry that districts will seek to replace full-time employees and their costly benefits with part-timers.