Simon Bridges admits his promise of smaller class sizes may not mean fewer students per classroom.

The National leader announced a new policy to reduce the teacher-student ratio, as a centrepiece of his conference address over the weekend.

However, many primary schools run "modern learning environments" with several classes in the same room.

Bridges told Kerre McIvor National's policy is about the number of staff per student, not the number of students per room.

" So in those modern learning environments, that may mean more teachers, but that doesn't necessarily mean smaller classrooms."

LISTEN ABOVE AS SIMON BRIDGES SPEAKS TO KERRE MCIVOR