I have heard many different opinions, maybe a better word is “attitudes,” about raising a bilingual child on the mission field and how to carry out the process. There are many myths that people believe, and some of them even come from the doctor’s office. With these myth’s going around, it can cause well-intentioned parents to be hesitant to teach their children or allow their children to learn in both languages at the same time.
Our oldest daughter is at that age of starting school, and now she learns in both English and Chinese. She will be learning to read, do the math, etc. but in what language? It is to these questions that I did some research and found these common myths about bilingual children.
Below are excerpts from an article naming the myth and then giving select commentary on each one.
Myth #1 – “Growing up with more than one language confuses children.”
“From just days after birth, all infants can tell the difference between many languages,” says Barbara Zurer Pearson, author of Raising a Bilingual Child. She says this is especially true when the languages are quite different from each other – as different, for example, as French and Arabic.”
“At that young age, infants generally still have trouble telling two very similar languages apart, like English from Dutch. But by about 6 months of age, they can do that too,” she says.”
Myth #2 – “Raising a child to be bilingual leads to speech delays.”
“Studies have found that children with language delays who are in dual language environments gain language at the same rate as those in monolingual environments,” says Kester.”
Myth #3 – “Bilingual children end up mixing the two languages.”
“Mixing languages is both inevitable and harmless. But to some unfamiliar with bilingualism, it’s proof that the child can’t really tell the languages apart.”
“Experts agree that mixing is temporary. Eventually, it goes away as a child’s vocabulary develops in both languages and he has more exposure to each one.”
“Sometimes people do it because they don’t know a word they need in the language they’re speaking,” says Pearson. “Some people mix on purpose because they like the word or phrase in the other language better.”
Myth #4 – “It’s too late to raise your child bilingual.”
“It’s never too late – or too early – to introduce your child to a second language.”
“Learning a second language is easier for children under 10, and even easier for children under 5, compared with the much greater effort it takes adults,” says Pearson.”
“We hear so much about the special ‘window of opportunity’ for young children to learn two languages that it can be discouraging to the older child,” says Pearson. “It’s true that it’s easier to start earlier, but people can learn a second language even after the window has closed.”
Myth #5 – “Children are like sponges, and they’ll become bilingual without effort and in no time.”
“Although it’s easier for children to learn a new language the earlier they’re exposed to it, even then it doesn’t happen by osmosis. It’s unrealistic to expect your child to learn Spanish by watching countless episodes of Dora the Explorer on television.”
“Learning a language doesn’t have to be a chore. But introducing a second language to your children does require some kind of structure and, most important, consistency, whether it’s through day-to-day conversation or formal instruction. The idea is to expose them to language learning in meaningful and interesting ways that are connected to real life.” 
The above myths and portions are from a more extensive article that I would encourage you to read, click here, to get the full perspective on these myths.