ALTHOUGH the leaders of teachers unions and charter schools are often in warring camps today, the original vision for charter schools came from Albert Shanker, the president of the American Federation of Teachers.

In a 1988 address, Mr. Shanker outlined an idea for a new kind of public school where teachers could experiment with fresh and innovative ways of reaching students. Mr. Shanker estimated that only one-fifth of American students were well served by traditional classrooms. In charter schools, teachers would be given the opportunity to draw upon their expertise to create high-performing educational laboratories from which the traditional public schools could learn.

Mr. Shanker was particularly inspired by a 1987 visit to a public school in Cologne, Germany, which stood out for a couple of reasons. Teams of teachers had considerable say in how the school was run. They made critical decisions about what and how to teach and stayed with each class of students for six years. And unlike most German schools, which are rigidly tracked, the Cologne school had students with a mix of abilities, family incomes and ethnic origins. Turkish and Moroccan immigrants were educated alongside native German students in mixed-ability groups. Sixty percent of the school’s students scored high enough on exams to be admitted to four-year colleges, compared with 27 percent of students nationally.

Mr. Shanker argued that charter schools could help reinvigorate the twin promises of American public education: to promote social mobility for working-class children and social cohesion among America’s increasingly diverse populations. There is considerable research to back up this vision. Richard M. Ingersoll, a sociologist at the University of Pennsylvania, has found that where teachers have more say in how their school is run, the school climate improves and teachers stay longer — trends that have been independently associated with increased student learning. And data from the National Assessment of Educational Progress in Mathematics show that low-income fourth graders who attend economically integrated schools are as much as two years ahead of low-income students stuck in high-poverty schools.