Increasing numbers of students are opting not to take Minnesota Comprehensive Assessments (MCAs) — a troubling trend that could make the statewide data less valuable to schools and teachers trying to improve learning.

Just under 2% of the state’s nearly 700,000 public school students (grades 3-12) declined to take the math test last year, while about 1.5% opted out of the reading assessment. Even though the overall opt-out numbers are relatively low, more schools are finding larger percentages of their students declining to take the tests.

That’s unfortunate. The MCAs are Minnesota’s only statewide evaluation of learning and are valuable in comparing the performance of students and schools. The results can help teachers guide instruction — a benefit that school districts need to emphasize to students and their families.

All Minnesota public schools are required to administer the MCAs, which are designed to monitor adherence to academic standards and to comply with federal standards. At the same time, both state and federal rules allow students to opt out.

Reading and math MCAs are administered each year to students in third through eighth grades, and fifth- and eighth-graders are also tested in science. High school students take a reading exam in 10th grade and a math test in 11th grade, as well as science exams in years when they take specific science courses.

Nearly half of eligible students at Hopkins High School chose not to take the MCA math test last year — a number that worries Principal Doug Bullinger. “A very key piece of the puzzle is missing when people look at this data,” he told the Star Tribune.

Minneapolis has some of the highest opt-out rates. Last year, 91% of students at Patrick Henry High School declined to take the math test, and 85% sat out the reading test. When kids opt out, they are counted as “nonproficient,” thus distorting the data for their schools.

The pushback against testing began to pick up speed during the No Child Left Behind era of federal requirements that required testing and used it as the sole measure to evaluate schools. During that time Minnesota briefly had high-stakes testing that tied graduation to testing, and many schools were labeled as failing. Local districts devised even more tests, and complaints grew about classroom time taken up with test prep and test-taking.

When the tests were recommended as measures of educator effectiveness, some classroom teachers began to encourage opting out. They argued that excessive testing limited the curriculum, while some parents objected to the added pressure on their kids. Some of those concerns were later addressed, in part to comply with recommendations from a 2017 report by the state Office of the Legislative Auditor.

School leaders hoping to reduce opt-outs can look to districts such as St. Louis Park for guidance. That school system has made its case to families by stressing how teachers use MCA data to make valuable changes in the classroom. As a result, test participation rates have not only stabilized, they’ve increased.