WHEN PEOPLE think of jobs related to science, technology, engineering, and math, or STEM as America’s relentless acronym makers would have it, they don’t usually think of blue-collar workers or applicants without full college educations. But a new report from the Brookings Institution reveals what it calls “the hidden STEM economy.” It estimates that about 26 million jobs in the United States require a high level of knowledge in one STEM field or another, but about half of those are attainable, in fact, to workers without a four-year college degree. These are in manufacturing, health care, construction installation, maintenance, and repair, and they pay on average $53,000 a year, which sure beats not working at all and is about 10 percent higher than jobs with similar educational requirements. Moreover, these sorts of jobs are spread all over the country, not just in urban centers. But here’s the problem: of the $4.3 billion the federal government spends to stimulate and improve education in science, technology, engineering, and math, only about one fifth goes toward the training of people who won’t get a bachelor’s degree. Community colleges are virtually ignored. Brookings advocates spreading the knowledge as well as the wealth.