One of the most frustrating myths about child bilingualism is that learning a new language is effortless for children – drop them into a new language environment and they just absorb the new language like a sponge! This myth has several negative effects. The first is that parents often don’t take into account the time and effort it will take, and add in too many languages, or add in new languages for short periods of time and expect their children to be quickly “fluent”. I’ve met parents who have seriously affected their child’s education and language development because they believed this myth and changed school language every couple of years, thinking it would be “fine”. The second is that it implies that any child who doesn’t absorb a new language quickly and easily is somehow challenged, when in fact it is the child who does who is exceptional, not the child who doesn’t. And the final (although I’m sure I could list a few more) is that it completely negates the experiences of children who are being put into situations were they don’t speak the language, by presuming that it will be easy for them. For most children, it is not. For many children, it is traumatic to be dropped into a school where you cannot communicate with anyone; neither be understood nor understand. This experience affects children differently of course, but over the years I’ve met many parents who just thought their child was being difficult or not trying hard enough, because after all, aren’t they supposed to be sponges!
This research article is important in contextualising the process of becoming bilingual (even from birth) as being an added cognitive load, and taking more time and effort. These are my favourite quotes, but the whole article is worth a read.
Hoff’s review of the research shows strong evidence that the rate of language growth is influenced by the quantity of language input. Her findings challenge the belief, held in and out of scientific circles that children are linguistic sponges who quickly absorb the language or languages they hear and will become proficient speakers of two languages so long as they are exposed to both at an early age.
“One clear implication of studies of bilingual children is that we should not expect them to be two monolinguals in one,” said Hoff. “The bilingual child, like the bilingual adult, will develop competencies in each language ‘to the extent required by his or her needs and those of the environment.'”
The full article can be found here: Children take longer to learn two languages at once compared to just one — don’t fret
on raising bilingual children 
I begin more and more to question the received acceptance of the ‘silent period’. When I watch it in action, and talk to parents about the reality of it, I wonder if it isn’t almost an infringement of a child’s right to talk. If you forbid the home language in school, you are condemning a child to silence for at least several months. There must be children for whom this is deeply traumatic and for whom it has long-lasting consequences. I wonder if we don’t have this idea (associated with the sponge myth) that they will bounce back, they will be fine etc. I haven’t read anything in depth about it….but I wonder if they really are fine?
I completely agree Nell. There isn’t (that I know of) any research on the impact on children, but I’ve certainly met many children who were traumatised by being dropped into a “school language only” environment. I’ve met several children who were selective mutes at school, including one who hadn’t spoken at school for 8 years! And that’s only mentioning the most visible cases, and there are, I’m sure, many many more who just disengage and do poorly in school because they don’t feel safe or valued. And that’s not fine!
Thaanks for the post