Minnesota students will resume taking the Minnesota Comprehensive Assessments on Friday following assurances from the state's testing vendor that new steps have been taken to prevent a cyberattack like the one that halted exams earlier in the week.

Education Commissioner Brenda Cassellius, who has repeatedly called the testing disruptions "unacceptable," said Pearson officials told her they have installed new filters that will block hackers attempting to hobble the system. In 2014, the company was awarded a three-year, $33 million contract to administer the MCAs, which were given exclusively online for the first time this year.

"This is Pearson's problem," Cassellius said. "I expected they had security with the package they sold us."

The Minnesota Department of Education suspended exams Wednesday after students across the state reported difficulty logging into the system and sluggish response times. Exams were temporarily halted for a day on April 21 after similar problems arose.

Pearson officials confirmed Thursday that the cyberattack that hindered test takers in Minnesota also affected students in Florida on Wednesday. There, state education officials advised school districts to suspend tests after students had problems logging on to standardized biology, civics and history exams.

About 30,000 Minnesota students have yet to finish the MCA science exams, which must be completed by Tuesday. Cassellius said she didn't consider giving students more time to take the MCAs based on the fact that about 95 percent of the statewide exams are now completed.

As students scramble to finish the MCAs, questions continue to mount about the validity of this year's test results.

Education Minnesota, the statewide teachers union, released the results of a survey taken of more than 500 teachers that revealed 90 percent of respondents believed the computer disruptions last month affected test scores.

"The system used to evaluate schools broke down in many districts," said Denise Specht, the group's president. "These schools shouldn't be punished for the failings of the state's testing vendor. For those districts, the state should drop the high stakes from this year's assessments."

Department officials announced this week they would be hiring an outside firm to investigate whether the disruptions affected test scores. That work is expected to begin this summer.

There is currently a Senate proposal that would empower the state Department of Education to set aside the MCA results of school districts that experienced problems.

When asked if she supported such a move, Cassellius said that the state is required by the federal government to have a school accountability system in place and MCA scores play a pivotal role in Minnesota's system.

She also said that some schools have reported that they are satisfied with this year's MCA scores. Many rural schools did not experience problems, she said.

Two years ago, the state's relationship with its previous testing vendor, American Institutes for Research (AIR), soured when an estimated 15,000 students from 400 schools encountered issues logging on to take the MCAs — or had their sessions timed out early. A consultant hired by the state later determined that the disruptions did not affect student scores.

Kim McGuire • 612-673-4469