Some Northland 6-year-olds have attended up to eight schools because of their families' constant moving.
Te Tai Tokerau Principals Association is so concerned it is collecting data about transient students from 80 schools to determine the extent of the issue.
Leanne Otene of Manaia View School said students who hop between schools were the biggest problem facing schools in the region.
"I've got some kids now that are 6-years-old and have been to eight schools already," Ms Otene said. She estimated that if her school had 200 students at the start of the year, by the end of the year 80 would be replaced by new students.
It was very rare that students were moving to another school but rather moving out of the area, Ms Otene said. Most of the new students coming into the school are below, or well below, the expected learning level.