New classrooms - and air conditioning - will greet some of the 810,000 NSW students starting school in 2019.
Eight new and nine renovated public schools will open for the first time, providing an extra 400 classrooms capable of housing thousands of students.
It is part of the NSW government's $6 billion education infrastructure blitz, with 170 schools to be built or revamped over four years.
Education Minister Rob Stokes says the coalition is responding to a "once-in-a-generation opportunity" to provide the facilities students need to succeed.
The government is spending $847 million on school maintenance and $500 million on air conditioning.
Two new schools have been built for students with disabilities in Dubbo and Narellan while a 60-room high school has been built in Ballina on the NSW north coast.
Sydney's Manly Vale Public School received a 40-room upgrade while a 30-room senior campus has been built at Cammeraygal High School in Crows Nest.
It's the largest education infrastructure spend in the state's history, Mr Stokes says.
About 88,000 staff, including 900 new teachers, have been hard at work preparing for new classes in core subjects under a revamped syllabus first rolled out in 2018.
Year 12 students will be NSW's first class to take their final exams in the new English, maths, science and history subjects.
Students will also be allowed to graduate with an Australia Tertiary Admission Rank, or ATAR, by taking the easier English Studies course which was formerly a non-ATAR unit.
It is the final step in a curriculum overhaul begun in 2017.
The education department will be hoping for a smooth start to the year after the government was forced to apologise for putting the wrong date on the official certificates of students who completed their HSC in 2018.
Tuesday is the first official day of the school year, with most students returning to class during the week.
Australian Associated Press