It hasn't been pretty for Minnesota student testing this year. Twice this spring, online statewide testing has been suspended because of cyberattacks. In both cases, the evaluations proceeded in a few days, but the problems fueled calls for refunds from the testing company and further damaged test credibility.

The state's teachers union says this year's Minnesota Comprehensive Assessment (MCA) scores should be thrown out, arguing that they can't be trusted to help evaluate how students and — for the first time this year — how teachers are performing. And a small but growing number of students — mostly in Minneapolis — have chosen to opt out of the tests.

The security issues are serious, but evaluating students through standardized tests remains important in measuring student achievement and teacher effectiveness. Abandoning testing would be a mistake.

The Minnesota Department of Education (MDE) pays its vendor, Pearson, millions of dollars to administer the tests. State officials should demand satisfactory performance from here on out and at least consider whether Minnesota should consider another vendor.

As for the opt-out movement, there are a variety of reasons that parents and students reject tests, and some are justified. During the last decade under federal No Child Left Behind rules, many districts believed they needed additional tests to be more accountable. They devised their own exams, in part, because they weren't getting the information they needed to improve achievement from state tests or because they didn't receive state results in a timely manner.

That led to "test creep,'' which in Minnesota resulted in students taking 21 mandated state and federal exams between third and 12th grades, not including district-imposed tests. It's no wonder that many parents and students pushed back. And that's why Gov. Mark Dayton and key lawmakers made test reduction a key component of their education platform and recommended slashing the number of exams by one-third.

The student opt-out movement has picked up considerable steam in other parts of the country. In Minnesota, only a small number of students have made that choice. In 2013, 328 refused to take the MCA math tests, compared with 611 in 2014. Most of those came from two high schools, Minneapolis South and Southwest, where more affluent, high-performing students opted out, causing schoolwide math scores to plummet.

Not having a complete picture makes it more difficult for administrators and teachers to accurately track how students are doing and react accordingly. And if growing numbers of students choose to opt out in the future, it could lead to violations of federal law and affect school funding.

There's no reason for Minnesota to abandon exams. Once the current problems with test administration are resolved and state officials adopt some of the legislative proposals to streamline testing, there should be fewer reasons for parents and students to opt out.