The researchers analyzed the distribution of students from schools in the third grade of basic education, whose school record contains the indication of foreign birth, to calculate the segregation index by municipality and by school. In the first case, they concluded that almost a quarter (23%) of the 93 municipalities under analysis had "high segregation" values, especially in the Metropolitan Region of Lisbon. The segregation index calculated for 404 schools in mainland Portugal, which allows verifying how immigrant students are distributed among classes within the same school, shows that a third of schools (34%) segregate these students in their classes. "What seems to happen in these schools is that students with more difficulties are placed alongside others with equal problems, perpetuating segregation", explained Luís Catela Nunes, referring that the study found cases of schools where this discrimination is around 50%. More than factors of socioeconomic inequality, for example, it is the results of schoolchildren who are guilty of segregation