A fair number of the children I see as an educational psychologist are
from multi-lingual environments, e.g. a five-year-old girl with a
German mother and Kuwaiti father. The parents are highly educated and
speak fluent English in addition to their native languages. This
little girl grew up speaking these three languages. She was placed in
the French speaking section of an international school in France. Her
teacher is bi-lingual French/English, and the child has lots of
support at home. The parents and teachers feel however that she is
floundering and losing heart, and are querying whether or not they
should perhaps stop speaking either Arabic or German at home. I have
assessed the girl, and she is of average IQ with slightly depressed
expressive and receptive language skills in English. I cannot assess
her in French.

This case study is typical of the families I work with. I am
frequently asked how many languages can a child cope with; is it
important for parents to speak either in one language or the other and
not mix the two in one conversation or even one sentence (this often
happens and seems intuitively wrong to me)?