The blaze Sept. 28 forced officials to cancel classes at Mary Duncan School in The Pas.
The province says foundation and electrical work will begin immediately to prepare for five portable classrooms.
In the meantime, about 55 students in Grades 5 to 12 will continue classes in Guy Hall, which is part of the local church.
Daycare space in the school was also damaged.
Four young people between 12 and 16 are charged with arson.
"The school division is very appreciative of the response from the local fire departments, the community and the Department of Education and for their support during this difficult time," Doug Long, superintendent of the Kelsey School Division, said in a release Thursday.
"It has helped the students and staff begin the process of moving forward."
Children attending the daycare are being accommodated in the church basement.
The adult learning centre has been temporarily relocated to the University College of the North.