In places where I live some private institutions are forcing students (of age 6 to 17) to speak only in English, regardless of their native language. This restriction is not only placed in English class but on the entire school premises, except other language classes. The purpose of these restrictions are to help students improve their English. Also, these institutions fine and punish students who speak in the native language within the school.
Some activists have claimed that the punishments will make students think ill of their native language and make them stop speaking it elsewhere too. I too think that could happen as children spend a great deal of time in school. Also, they claim that their vocabulary and fluency in their native language will be reduced.
I saw in a similar question that forcing students to speak in a language helps students to acquire knowledge of a second language. But will it affect their knowledge of their native language? Will it reduce the fluency and vocabulary in one's native language?