Teachers are lousy students. They were poor with the books entering college, weren't all that hot leaving it and have no real economic incentive to stay in a maligned profession.

The school boards and the state legislatures aren't doing much to help either. They don't pay enough attention to quality and haven't come up with the cash to attract and keep those who teach your children.

That's the gist of a message Secretary of Education Terrel H. Bell has been preaching to various education groups since he joined the Reagan Cabinet to preside over the dismantling of his department.

"I think our teacher personnel practices are really outmoded. The way we pay teachers, the way we educate and license them, the promotion opportunities for teachers are just not there," he said at a recent lunch with Washington Post reporters and editors.

The gloomy picture Bell paints is borne out by recent testimony on Capitol Hill that Scholastic Aptitude Test scores for education majors have dropped far more than those in most other fields. He even offers solutions. Higher admissions standards for education majors, competency tests for teacher graduates as well as students, cash bonuses and recognition for good teachers.

"We have almost a fatal obsession with the single salary schedule," Bell said. "I think every state ought to set aside a certain percentage of their money every year and earmark it" for some bonus system.

The ideas about competency testing are being tried in 17 states, although early experience in Florida already is causing controversy. Overall, 80 percent of the 4,340 students who took the test passed. But two-thirds of the 435 blacks tested flunked, the state announced earlier this month.

The suggestions about states coming up with more cash have gone nowhere. Some experts blame the teachers' unions for opposing anything but across-the-board raises. Some just say states are strapped for routine operating funds, much less bonus money.

Bell also criticizes the nation's school boards. "I think of all our public officials, those who are neglecting their duties just about as much as anybody are the locally elected school boards," he said.

"You read a school board policy manual and you'll read about how to handle bus routes, how to rent out the building, and all of those routine business affairs, but you won't see anything there about academic quality, incentives for learning," the secretary said.

He said that boards should enforce "time on task" to make sure the 180-day school year isn't eaten up by football and proms, instead of academics.

School board officials have long complained that their time is consumed with budget crises, school-closing decisions and the like, with little left for long-term study of curricula.

Recent congressional testimony by Milton Goldberg, head of the National Institute of Education, paints a discouraging picture about the aptitude of the nation's 2.4 million teachers.

He noted, for instance, that the average Scholastic Aptitute Test verbal scores among education majors entering college declined between 1972 and 1980 from 418 to 339. Math scores fell as well, from 449 to 418. Both declines, he said, were steeper than the average 20-point drop experienced by other majors.

Other tests showed education majors near the bottom as well. Test scores of education graduates have declined too, Goldberg said.

Much of the decline, he said, is attributable to the fact that the brightest young women are not becoming teachers as they used to. Instead they are entering law, medicine and the sciences, fields once not open to them.

Goldberg's testimony was based on a study by NIE's Gary Sykes that recited the test scores and said: "In short, a mass of evidence converges to show that academic ability of education is both low and declining. Teaching appears to attract the least academically able and to be decreasingly attractive."

Sykes noted though that the low academic ability of teachers is a historical fact. He cited similar test results back to 1928.

Statistics also show that the most able teachers are the first to leave the profession, and that the teacher workforce is aging. Because of the glut of teachers nationally, the number of education graduates has dropped from its high of 317,000 in 1972 to 160,000 last year.

Terry Herndon, executive director of the 1.7-million-member National Education Association, said in a recent interview that he couldn't dispute the facts of declining education major test scores.

He said he had long been an advocate of higher standards at teacher colleges. The short-term outlook for improvement is "very grim," he said, unless there is some shift in the national mood, such as followed the first Soviet space shot in 1957.

The answer to the problem, he said, "is more money. If we don't change the economics of the profession, the problem won't be solved. If you fired all 2.4 million teachers and started over in the same economic environment, you would come up with the same slice of the talent pool."

NEA went to the wall for President Carter and lost in the last election, and opposes the Reagan administration's plan to abolish the Department of Education. "Ronald Reagan talk about his belief in education and the cause of excellence is just a lot of hogwash," Herndon said.

NEA opposes competency testing as a condition of employment, saying no single test is adequate. The rival American Federation of Teachers supports such testing for new teachers.

Bell said he thinks the American educational system has been "showing quite a few of the dinosaur symptoms of not adapting when something comes up . . . . I think there are a lot of practices that need to be changed. Myself, along with a lot of others who have the pulpit to do it, ought to be constructive critics of education."