Speaking at Cressy District High School on Saturday, Mr Rockliff said some college teachers may go into high schools to teach or the system would rely on university graduates.

The state government announced on Friday that 18 more Tasmanian high schools would offer year 11 and 12 subjects from next year.

Until recently, Tasmania’s public schools only offered a full curriculum up to Year 10, with students transferring to one of eight colleges to finish secondary years.

Twelve high schools have already extended under the $45 million state government initiative.

Mr Rockliff said specific teaching numbers for the 18 new extension schools had not been decided.

‘‘The number of teachers always depends on enrolments in any given year,’’ he said.

He said extending schools had ‘‘12 months effectively to plan and prepare’’ what subjects it would offer and how many teachers they need to suit learning model.

‘‘If we get an overwhelming response and have more students moving on to year 11 than we expect - and that will be a wonderful thing to happen - the teacher resource will be there,’’ Mr Rockliff said.

Cressy District High School principal Craig Brown said staff already at the school may ‘‘start teaching years 11 and 12 (next year) and they might be replaced by other teachers’’.

‘‘Or it might be we bring teachers in,’’ he said.

Former Braddon Greens MHA Paul O’Halloran, who was a Don College teacher for 15 years, raised concerns on Saturday that the extension of North-West high schools would have a negative impact on the coast’s colleges.

‘‘To say that they will run alongside each other, I just can’t comprehend,’’ he said.

Mr Rockliff reiterated that extending high schools is not about replacing colleges.

‘‘It’s about adding to the number of post-Year 10 students, who otherwise wouldn’t continue to Years 11 and 12, and this will be done in partnership with colleges,’’ he said.