Former New York City mayor Michael Bloomberg says President Obama’s effort to reduce standardized testing in public schools is a “grave mistake.” (John Minchillo/AP)

Former New York City mayor Michael Bloomberg says that President Obama and Education Secretary Arne Duncan are “making a grave mistake” by pledging to reduce the amount of standardized tests mandated in U.S. schools.

In an essay first published Tuesday by Bloomberg View, which he owns, the former mayor has harsh words for the president and his education secretary, accusing them of “caving to pressure from union leaders and a vocal subset of parents.” He said their actions could do “real harm to our poorest students and America’s future.”

Bloomberg wrote that “students will face tests throughout their life. They must learn to cope with the emotional stress that comes with the experience, particularly because many companies (including mine) use tests in hiring. I understand: Test-taking is no one’s idea of fun, but it is part of life and shielding students from it does them a great disservice.”

He suggested that cutting back on testing will reduce pressure on schools to educate all children and will ultimately harm the country.

“In the ultracompetitive global economy, the U.S. is facing a terrible mismatch between high-skill jobs and our labor pool,” Bloomberg wrote. “This problem will grow worse over time unless we expect more of ourselves and our students — and hold everyone, including teachers and school leaders, accountable for success. Caving to pressure from union leaders and a vocal subset of parents who want to end testing and accountability will make it harder to achieve that success.”

During Bloomberg’s tenure as mayor, the state legislature transferred responsibility for the nation’s largest school system to the mayor instead of a school board. He aggressively pushed through policy changes, including a teacher evaluation system based on student test scores and a rapid expansion of public charter schools. His schools chancellor, Joel Klein, emphasized the use of test score data to drive decision making.

Bloomberg, the three-term mayor who left office in 2013, was responding in his essay to an announcement on Saturday by Obama in which the president said there is too much standardized testing in public schools and promised to take steps to reduce it.

In “moderation, smart, strategic tests can help us measure our kids’ progress in school, and it can help them learn,” Obama said. “But I also hear from parents who, rightly, worry about too much testing, and from teachers who feel so much pressure to teach to a test that it takes the joy out of teaching and learning, both for them and for the students. I want to fix that.”

The Obama administration said it would work with states and local school districts to help them assess the quality and quantity of their tests to get rid of redundant or low-quality exams. It said it also would consider adjustments to its own policies to reduce overtesting. And it recommended that states consider capping the amount of time devoted to standardized testing at 2 percent of instructional time.

Obama’s move came on the heels of the first comprehensive report on standardized testing in K-12 schools, which found that most schools require too many tests of dubious value.

A typical student takes 112 mandated standardized tests between pre-kindergarten classes and 12th grade, according to the study carried out by the Council of the Great City Schools, which represents the 66 largest districts in the country. By contrast, most countries that outperform the United States on international exams test students three times during their school careers.

The heaviest testing load falls on the nation’s eighth-graders, who spend an average of 25.3 hours during the school year taking standardized tests, uniform exams required of all students in a particular grade or course of study. Testing affects even the youngest students, with the average pre-K class giving 4.1 standardized tests, the report found.

It portrays a chock-a-block jumble, where tests have been layered upon tests under mandates from Congress, the U.S. Department of Education and state and local governments. Many of these tests, the study argued, have questionable value to teachers and students. Testing companies that aggressively market new exams also share the blame, the study said.

Bloomberg suggested that Obama and Duncan were reacting to the political fallout over low test scores that states have begun reporting from new state tests aligned to higher academic standards. The new, more demanding tests were given in most states for the first time in the spring.

“Yet now that results from tests aligned to these standards are showing just how many students are not on track for college, the public backlash against the tests seems to have given Obama and Duncan a case of cold feet,” Bloomberg wrote. “That’s deeply regrettable.”