CALGARY -- A request by the Calgary Board of Education and Calgary Catholic School District to temporarily shift Grades 7 to 12 to at-home learning has been approved by Alberta Education.

Students will shift to at-home learning on April 19 for two weeks.

The decision is based on four criteria; a chronic substitute teacher shortage, a significant number of students and staff in quarantine or isolation, recent requests from the board for short-term shifts for a number of their schools and substantial COVID-19 cases in the community.

"While everyone’s preference is to learn in school, some school boards are dealing with operational pressures due to rising COVID-19 cases in the community. The safety of students and staff is my top priority, which is why I am responding to the boards’ requests and respecting their autonomy. By having a clear process in place, we are giving them flexibility to move to at-home learning when necessary," said Adriana LaGrange, Minister of Education in a statement.

"We are seeing a sharp rise in cases among school-aged Albertans, as well as those in other age groups. While this is an operational decision, I support it and ask that parents and students continue making safe choices to reduce the spread of COVID-19. Social activities outside of school can easily spread the virus, so please continue following all the health measures in place," said Dr. Deena Hinshaw, chief medical officer of health.

More than 6.700 Calgary students and staff are currently in isolation, several city schools have moved some classes temporarily online and the Catholic school board is again pushing for staff to be vaccinated to protect them from COVID-19.

"We feel that our teaching staff and our support staff, custodial staff are vulnerable," said Mary Martin, Calgary Catholic School District board chair.

"It becomes very clear and very evident that we need to do all that we can to advocate for the supports that they need, and that means prioritizing our frontline school staff for vaccination."

As of Tuesday, Dr. Deena Hinshaw said 19 per cent of Alberta's schools are dealing with an outbreak of COVID-19 and thousands more people are isolating due to possible exposure to the virus.

According to CCSD, 35 of its schools have at least one active case of COVID-19 and 13 are in outbreak status. The school board says 2,078 students and 167 staff members are in isolation due to being a possible close contact with someone who has COVID-19.

Six of its schools have had to move some of its classes to temporary online learning.

"We're in the middle of an unprecedented pandemic and it's very clear that we have many miles to go on this front," Martin said.

The Calgary Board of Education has nine schools -- two high schools and seven junior high schools -- that have moved some classes online temporarily. The CBE says 4,300 students and 240 staff members are currently isolating.

"Teachers have been dealing with a difficult school year all along, with health protocols and COVID-19," said Jason Schilling, the president of the Alberta Teachers Association.

"I've talked to colleagues who have had to quarantine four or five times this year alone and it creates a lot of challenges and the increase in cases we're seeing right now is very concerning," he said.

Across Alberta, there are 453 schools experiencing outbreaks and 2,653 cases of COVID-19 have been linked to schools since Jan. 11.

With files from CTV Calgary's Jordan Kanygin