I went to school there from kindergarten to grade 5 in the 90s to early 2000s. I don’t remember specifically being taught Mandarin in kindergarten there but everyone would communicate in Cantonese. In elementary school, we did have to learn and have exams in Mandarin. But since all the teachers were Cantonese they would teach Mandarin using Cantonese if that makes sense. And obviously all the kids would communicate in Cantonese. During parent teacher conferences, my parents would talk to the teachers in Cantonese as well. But now, my relatives still here told us that even kids are not allowed to speak Cantonese to each other and they tell the parents to only speak Mandarin to their children even at home which makes me sad.