In the pilot phase of the program, the tests caused "a real financial hardship for school districts with no evidence that it increased student achievement," the letter says.
In addition to the letter, the Haverford Township school board on Thursday passed a resolution opposing the new regulation. Radnor did the same thing last month.
The State Board of Education in September approved the so-called Common Core standards, which require all students to pass proficiency tests in science, math, and language arts before graduating. Plans call for students to take Keystone tests in up to 10 subject areas in coming years.
The standards are a voluntary initiative that establishes proficiency requirements for kindergarten through 12th grade. So far, it has been adopted by 45 states.
In Pennsylvania, the regulations still need approval from the IRRC, a panel appointed by lawmakers and the governor, and the House and Senate. The IRRC is slated to consider the plan Nov. 21.
The public is allowed to submit comments up to two days before the meeting.
If approved, the standards would take effect with the current crop of ninth graders when they graduate in 2017. They would need to pass Algebra I, Biology I, and language arts.
If they fail, they could retake the test. If they fail again, they could do a supplementary project, but that would be noted on their diploma.
The letter writers said implementing the project would require substantial human and financial resources "such as project administration, student tutoring, and project assessment by a Pennsylvania-certified teacher."
Test supporters argue that tens of thousands of students now graduate without needed skills and that they should be able to pass a competency test to receive a diploma.
Frank Gallagher, superintendent of the Souderton School District, said his not signing the letter "wasn't an intentional thing. A lot is going on." However, he said, the district is not opposed to the idea of the Keystones, though it objects to the state's dictating when they must be administered.
For schools that have participated in the pilot program, administering the exams has created "unanticipated hours of planning for test preparation, administration, remediation, and review," the letter says.
Students spent up to three to four weeks taking the Keystones, AP exams, and their schools' final exams, the educators said. In addition, students also take college entrance exams in the spring.
The plethora of tests is an "undue burden on students and wastes precious teaching time for exam review," the letter says.
Haverford superintendent William Keilbaugh called the Keystones "an operational nightmare."
Moreover, for students who have learning disabilities or are not good test-takers, "you're going to create right out of high school second-class citizens," he said. "There has to be a better way."
BY THE NUMBERS
Out of 62 superintendents in the Pennsylvania suburbs signed a letter stating their opposition to the Keystone exams.
Maximum number of subjects in which students may be tested in the Keystone exams.
States that have adoped the Common Core.