The research examined whether the allocation of students to classes by socio-demographic characteristics (such as parents' education level) in primary and middle (junior high) schools in Israel during 2001–10 is random or not, based on conventional indices of segregation.
There is very little segregation within primary schools: generally, in a grade with 100 students, even the transfer of only one student from one class to another is enough to reach random assignment. In the Arab educational system, segregation is higher than in the Hebrew education system. There are almost no differences in segregation by school characteristics or class level, or over time. Segregation within schools (in the Hebrew education system) is about 10 percent of the segregation between and within schools, combined.
Since middle schools are larger than primary schools, as are their catchment area, the segregation indices between middle schools are lower than in primary education; for the same reason, the indices within the middle schools are higher than in primary schools, particularly in the Arab educational system and for immigrants from Ethiopia in the Hebrew State-Religious education system, though those are narrowing. All in all, segregation within middle schools is similar to that in primary schools. Thus, the concern that integration policy in middle schools will lead to segregation within the schools, came about to only a very limited extent.
Segregation between schools in the Hebrew educational system is greater than in the Arab educational system, due to the greater socioeconomic heterogeneity in the former. In the Hebrew educational system segregation between schools is ordered by the following descending ranking: ultra-Orthodox, State-Religious, State. Over the years, the indices of segregation increased markedly between primary schools and between middle schools in all educational streams, especially with regard to immigrants from Ethiopia.

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