Te Awamutu principal Gareth Duncan said he had taken advice from medical officer of health Dr Dell Hood early in the outbreak about preventing the spread by avoiding situations such as large gatherings of students.
Instead, Mr Duncan is broadcasting the assembly information directly into the classrooms via the school's radio station.
At Te Awamutu College, where the 11 teenagers first infected study, acting principal Neil Bauernfeind said the school had not been advised to take the precaution but it had taken other action such as warning parents of the risks to unimmunised children.
Some of the teens first infected were now back at school.
So far this year there have been 181 confirmed cases of measles in New Zealand, including 104 in Greater Auckland.
Of those, 19 were admitted to hospital.