TLDR: Children of immigrants are treated as native speakers when learning a heritage language despite the fact that the language is destined to be their second-language. The method of instruction needs to reflect that as well, rather than drive them away.
Immigrants to North America typically want their children to become fluent in their heritage language. In early years, parents often speak this language with their children which enables them to become fluent. When these children start school though, their English starts to rapidly develop as it is the primary language of instruction and socialization with their peers. At this stage, children will typically start predominantly speaking English at home as well (even if spoken to in the heritage language).
At this stage, the development level of the heritage language will dramatically slow as the child doesn’t interact with the language. When children travel back to their heritage country and interact with extended family there, this stunted linguistic development becomes more striking as they are naturally compared to peers at a similar age.
Returning back to their new home, parents often look for local solutions to close this gap. Input from heritage language TV, books, apps and other media is one approach. Another, is to enroll the child in after-school classes, Unfortunately, most efforts fail as the experience for the child is usually not fun and enjoyable. Heritage-language media lacks the long-term structured approach and social environment for interaction. Heritage-language classes are typically taught with inappropriate approaches that are designed for native-language speakers and not for students where this heritage language will be a second-language for the child. This fundamental error in approach, more often than not, results in destroying any interest the child has in the language and ends up driving them away - the exact opposite result of the parents’ intention!
Parents need to realize that their children should learn the heritage language differently than they did.
TLDR: Teach immigrant children using techniques appropriate for foreign-language speakers because that is what they are.
The solution is a structured, tutoring center-based approach where the child has fun learning the language, while the parents see continued improvement and interest in the heritage language & culture.