Middle class kids from educated families get this all the time. They get it at home, they get it in clubs, they get it in churches, they get it a variety of places. At-risk kids may or may not. So this is one vital condition. The second one goes like this.
Language development is a meta-goal of instruction across the school day.
Language development is the primary focus and content of all development for at-risk kids. So if instruction is in English, English language development is the meta-goal of the school day. If the language of instruction is Spanish or Navajo, then development of that language is the primary focus and if you have dual programs then each in turn is the primary focus. We also by this emphasize the development of the languages of content. So that kind of language development is the first order of business of the school day.