More than 65,000 Colorado students were held out of last spring’s PARCC tests by their parents, according to newly released data that for the first time documents the strength of the so-called opt-out movement in the state.

Roughly 1 in 10 Colorado students skipped the math and English assessments as a result of parent refusals.

Test-taking rates were high with young students, began to sink in higher grades and plummeted among high schoolers, many of whom saw little value in sitting for yet more standardized tests as they prepared for the next chapters in their lives.

While test participation by elementary school students exceeded 95 percent, student opt-out rates reached 31 percent on 11th grade math tests and 25 percent on all 10th grade math scores.

Across all grade levels and in both English and math, white students were far more likely than their black and Latino classmates to miss the tests as a result of parental refusals.

At a press briefing Thursday, interim education commissioner Elliot Asp acknowledged a concern about how representative the scores are in higher grades that saw large number of parental refusals, most likely in affluent areas.

Colorado was portrayed as one of the epicenters of the opt-out movement last spring, but until now no firm numbers were available about the scope of the phenomenon.

Anti-PARCC sentiment was fueled by protests the previous fall of state science and social studies tests that saw mass refusals from students in mostly affluent, high-performing suburban school districts.

Data Center | Search our 2015 PARCC opt-out database here.

More granular detail about opt-outs in Colorado will become available Dec. 11, when state officials are expected to release test results and participation rates of individual districts and schools.

Only the state-level picture was available in Thursday’s release, which showed most Colorado students well short of where they need to be in mastering English and math academic standards.

The tens of thousands of opt-outs all but certainly drove down Colorado’s numbers, although to what extent is not known.

In all, 65,858 students in grades 3 through 11 missed PARCC English tests as a result of parental refusals, state data shows. The total was 47,852 students in grade 3 through 10 in the math exams. Presumably most parents who refused to allow their children to take PARCC did so for both tests. The refusal rates for both subjects closely mirrored each other.

Thousands more Colorado students missed the exams, without their parents or guardians officially opting them out. Those students could have been absent for other reasons — such as illness — or may have skipped out of protest without saying so.

The total participation rate was 82 percent for the English tests in all grades, and 85 percent for the math tests.

Ilana Spiegel, a Cherry Creek School District parent who served on a state task force that recommended reforms to state testing, said the high number of opt-outs seriously called into question the validity of the PARCC scores.

The movement to skip the tests includes a number of motivations, she said, including people upset with standardized testing in general, the PARCC tests in particular, or using the tests to hold schools, districts and teachers accountable.

“I think you will continue to see more (opt-outs) as people say they don’t want this to be the new normal,” Spiegel said.

Testing reduction and opting out were hot topics during the 2015 legislative session. An assessment bill was passed – among other changes seniors won’t be tested this fall – but a measure to codify parent opt-out rights died in a House committee.

Test participation rates are important because the U.S. Department of Education requires 95 percent test participation. In Colorado, schools and districts can see their accreditation ratings downgraded if they fail to meet that benchmark on two or more tests.

The state board, however, voted earlier this year not to penalize districts that don’t meet participation requirements this year — an issues central to the state’s request for flexibility from the No Child Left Behind federal education law.

A Chalkbeat Colorado canvassing of the state’s 20 largest districts last summer found only five that provided responses tested enough students on PARCC to meet the 95 percent bar.

The following graphic documents opt-out rates from English language arts tests …

PARCC opt out rates by grade and race