Students should only be tested if symptomatic and further rapid tests would be provided to schools to distribute as required, Premier Peter Gutwein said.
Students or teachers won't be considered a close contact and required to isolate if there are a "small number" of infections in a classroom.
If there are five or more cases in a classroom within a week, the scenario will be managed as an outbreak.
Students will still be required to abide by the household close contact rules, which require people to quarantine for seven days if they've visited the house of a case for more than four hours.
"The public health advice is really clear, and that is schools are safe. The best place for children to learn is in a school," Mr Gutwein told reporters.
Masks are mandatory for teachers and for high school students, but not for primary school students or in early education.
Lunch breaks will be staggered under the plan, which is in place for at least five weeks.
State Health Commander Kathrine Morgan-Wicks said it was "critically important" children have a least one vaccine dose before returning to school.
Some 4600 kids aged 12 to 15 are not vaccinated and 44 per cent of children aged 5 to 11 have not been booked in for a first dose, she said.
Deputy Public Health Director Scott McKeown said household and classroom close contacts are being managed differently because of different risk levels.
"When a single case, or a small number of cases, occur within a classroom, they will be identified," he said.
"The education department will inform the carers and parents of those children and any staff in that learning group of a case.
"They will be advised to monitor their child or their student or as a staff member very closely for symptoms and get tested … if any develop."
Tasmania recorded 927 new COVID-19 cases on Thursday, with the number of people in intensive care increasing from two to three. Two of them are on ventilators.
Thirty-one people with the virus are in hospital, with 14 of those being treated specifically for virus symptoms.
An outbreak in a medical ward at Mersey Community Hospital in the state's northwest has forced the facility to move to level three of its COVID-19 management escalation plan.
The outbreak, described by health authorities as "contained", increased by one case on Thursday to 11 and includes nine patients and two staff
The medical ward is not admitting new patients and is not allowing visitors or transfers. Overnight elective surgery at the hospital will be reviewed on a case-by-case basis.
Staff are being requested to reconsider taking leave and all non-critical meetings have been cancelled.
Tasmania has 6127 active infections, a drop from Wednesday's figure of 6323.
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