The increasing role of standardized testing in U.S. classrooms is triggering pockets of rebellion across the country from school officials, teachers and parents who say the system is stifling teaching and learning.

In Texas, some 400 local school boards—more than one-third of the state's total—have adopted a resolution this year asking lawmakers to scale back testing. In Everett, Wash., more than 500 children skipped state exams in protest earlier this month. A national coalition of parents and civil-rights groups, including the NAACP Legal Defense and Educational Fund, signed a petition in April asking Congress to reduce federal testing mandates.

In recent weeks, the protest spread to Florida, where two school boards, including Palm Beach County, signed on to a petition similar to the one in Texas. A parent in a third, Broward County, on Tuesday formally requested that school officials support the movement.

The efforts are a response to the spread of mandatory testing in the past decade. Proponents say the exams are needed to ensure students are learning and teachers' effectiveness is measured. Critics say schools are spending disproportionate time and resources on the tests at the expense of more-creative learning. They also contend the results weigh too heavily in decisions on student advancement, teacher pay and the fate of schools judged to have failed.