Should my child keep the two languages separate in different situations and with different people (e.g. visitors)?

          One key idea in raising children bilingually is that of language boundaries. Language separation makes it easy for children to recognize when they should speak which language to which parent. Children also tend to create their own (temporary) language boundaries, particularly when they are very young. For example, in the one language-one parent situation, a child may get used to speaking one language to the father only. The expected language boundary is that all men speak that language. All women are expected to speak a different language.

How is language separation achievable? What strategies can be employed?           1. 'One language - one parent'. Each parent speaks a different language to the child who responds in that language.           2. Minority language only inside the home. Outside the home, the child will experience the majority language.           3. Speak the second language on certain days of the week - for example on weekends or alternative days. This has been achieved by bilingual families but the residual question is about its naturalness or artificiality.           4. A different language from the home is used at school or in another institution (e.g. when children use Hebrew in the synagogue or Arabic in the mosque, or go to Saturday schools and Sunday schools for language experience ).

SOURCE : A PARENTS' AND TEACHERS' GUIDE TO BILINGUALISM