A/HRC/43/47/Add.1 school model of immersion, indicating that schools in Catalonia were to teach at least 25 per cent of their subjects in Castilian, including at least one core subject. 58. The Catalan school system is based on a linguistic immersion approach for all children that privileges Catalan as the main, but not exclusive, language of instruction; it is claimed that all children in the system effectively acquire fluency both co-official languages. It has been suggested that if there were less exposure to Catalan, many children from Castilian-speaking environments would not learn Catalan properly, as it is a minority language, whereas Castilian remains a majority language in the country and is therefore guaranteed daily exposure and even prestige. The United Nations Educational, Scientific and Cultural Organization (UNESCO) and other international organizations have lauded the Catalan immersion approach. 59. The Special Rapporteur has received numerous reports from minority groups asserting two other main areas of concern in education. The autonomous communities of Catalonia and of the Balearic Islands are concerned that there has been a gradual erosion of existing educational approaches that had, until now, it is claimed, offered non-segregated immersion models that were largely successful in achieving effective bilingualism among most children. In some other autonomous communities, such as Galicia and Navarre, it was argued that existing educational schemes were insufficient to effectively guarantee that minority children could be educated in the co-official minority language. 60. Another point of concern for the Special Rapporteur was the absence of current empirical data on the impact of different educational models using immersion, bilingual or multilingual teaching methods. Such data had been collected throughout Spain before 2010. This lack of data collection may be feeding feelings that State authorities may not be fully meeting their obligations regarding the rights of minorities in the area of the use of language in education. It also may be creating concern among parents of non-minority pupils who feel they may be subjected to educational regimes that are harmful to their children’s academic achievement. 61. The Special Rapporteur reiterates that, in order to dispel such concerns and to properly assess the impact of various educational models using different co-official and minority languages, the Government of Spain should reinstate the collection of national data on the impact of different educational models. 62. The 2017 handbook on language rights of linguistic minorities highlighted the importance of providing education in a minority language. Where practicable, minority languages must be used as medium of instruction following general principles of proportionality. No one particular educational model is ideal or could possibly be appropriate for all of the different contexts of local populations or of the States involved. Nevertheless, the handbook does set out general principles, including the following: Where there is a sufficiently high numerical demand, public education services must be provided in a minority language to the appropriate degree, broadly following a proportional approach. This includes all levels of public education from kindergarten to university. If demand, the concentration of speakers or other factors make this not feasible, state authorities should as far as practicable at least ensure availability of minority language teaching. In addition, all children must have an opportunity to learn the official language(s).12 63. The handbook also makes clear that: Language differences must not be used as an excuse to segregate students along ethnic or racial lines in education. When open to all who share the same language, regardless of ethnicity or race, the use of minority languages as a medium of instruction is neither discriminatory nor impermissible segregation. To promote tolerance and inclusion, all students should learn about each other: minorities must not be prevented from understanding the culture and language of the national community as a whole or from participating in its activities, and the 12 Special Rapporteur on minority issues, “Language rights”, p. 16. 13