I come from Guangdong and study in the Pearl River Delta. Unlike upstairs, the quality of teachers in remote areas is not high, right? In fact, most teachers speak Mandarin in class, especially in primary school. The country is vigorously promoting Putonghua, and they will be punished for speaking Cantonese at school. At that time, dialects were basically not heard at school. In junior high school, local teachers in Guangdong will still teach in Cantonese. For example, my math teacher, physics teacher and biology teacher all teach in Cantonese, and I also try to teach Chinese teachers in Cantonese. Maybe it sounds more intimate. Students are also more receptive. Now in high school, teachers come from all over the country, and there are some students from other provinces in the class, so I have never seen any teachers teaching in Putonghua.