LLL_Sarah, There are hundreds of books and research papers on bilingualism. So I'm not sure. And I've read A LOT because of my research paper on raising bilingual kids in HK. Some books/articles I've read for my research went as far back as the 1960s. But in general, rule of thumb is not to go back more than 10 years (if possible)
Here though is an extract from Wigglesworth (for parents who are interested and deciding on creating relevant contexts):
In your readings, you may come across researchers who make the distinctions between primary contexts and secondary contexts. When used, primary contexts refer to situations where a child acquires both languages in a naturalistic setting without any structured instruction, while secondary contexts refer to the situation when a child acquires one of the languages in a structured setting, usually school. This creates a clear division where one language is acquired in a naturalistic setting and the other is acquired in a formal setting, usually a classroom. This distinction is sometimes referred to as natural bilingualism versus school bilingualism (Skutnabb-Kangas 1981).
Children who acquire both languages in a primary context acquire the languages as a result of natural input in the environment. This input is usually provided by caregivers, often the parents and/or siblings, when the child is an infant, but as the child enters early childhood, the input can also come from other sources, such as the extended family and the wider community. As we will see in Unit 3, there are many detailed reports on children being raised in bilingual situations like this ? often where one parent speaks one language and the other speaks another.
Within the primary context, a further distinction is made between naturalistic fused and naturalistic separate. In a naturalistic fused setting, there is no separation of context for both languages, and the child is exposed to both languages in the same context. So, for example a Mandarin-English bilingual child may receive input in both languages from each parent, siblings or peers. In such situations, both languages are used by the same speaker. In contrast, a bilingual in a naturalistic separate context may hear and use Mandarin only with one parent and English with the other parent. In this context, one language is associated with a specific parent. This latter model is commonly referred to as the one-parent-one-language model. Apart from parents, it is also common for the separation to be made according to other interlocutors such as siblings, peers and grandparents. So, in Singapore, a trilingual child may speak Mandarin to the parents, English to the siblings and Hokkien to the grandparents. More rarely, the physical environment is different, as in the case reported by Ginsberg (1996), where the child spoke to the parents in Spanish exclusively in the home, but in English outside the home; this system of separation was rigidly maintained throughout the child?s life. In this case, the child learnt to use the physical environment as a cue to switch between the two languages with the same interlocutors.
It is often assumed that language input in the pre-school years takes place in a naturalistic environment. While this is true for most bilinguals, for a large proportion of bilingual children in Asia, for example, Singapore, Malaysia and Hong Kong, structured language-focused teaching may begin when the child is as young as two. In Singapore, a child may speak both Mandarin Chinese and English without any formal teaching at birth but once they start attending childcare, which can be as early as two years of age, it is common for childcare centres to provide structured teaching in both languages. So, in such cases, the distinction between primary and secondary contexts may not be as clear-cut as in other settings.
The issue of primary and secondary contexts is important especially in the study of the language development in bilinguals as there is some debate about whether one context is more beneficial in promoting desired outcome in the language development of bilinguals.
I've kept a word copy of the book but I think it's illegal to publish it. I had access to it as a research student for my project. I am by no means a guru and my research was conducted 2 years ago now! Right now, I'm working on possibly writing a Language Programme Evaluation on Translingualisation (the new multilingual approach to language - particularly English) - which personally I think is a horrible way to learn English in HK - it's like a cop out!
I must say though, the latest research paper I just read (two days ago!)which reviewed succesful immersion programmes in 3 schools in Vic, Australia paved the way for the need for immersion for kids to pick up a language effectively - creating conditions for them to use it.
The reality is that the more you read about it (bilingualism), the more you realise that there is no right or wrong only creating situations for language development to blossom. As parents, that is probably our best bet. Just keep on creating conducive situations as long as it isn't burning a hole in your pocket!