Please answer a question about the following article about Catalan language:

Since the Spanish transition to democracy (1975–1982), Catalan has been institutionalizated as an official language, language of education, and language of mass media; all of which have contributed to its increased prestige. In Catalonia, there is no parallel of a large, bilingual, European, non-state speech community. The teaching of Catalan is mandatory in all schools, but it is possible to use Spanish for studying in the public education system of Catalonia in two situations, if the teacher assigned to a class chooses to use Spanish, or during the learning process of one or some recently arrived students.  There is also some intergenerational shift towards Catalan.

Where is the teaching of Catalan mandatory?
in all schools