Five-year-old Soo Song Xuan spoke almost no Mandarin two years ago.
His parents, businessman Soo Wee Kiat, 40, and Ms Vanessa Wong, 40, a personal assistant, used to converse with him mainly in English at home.
Worried that he would be unable to catch up with the mother-tongue subject in primary school, Ms Wong transferred him last year to EtonHouse International Education Group's Chinese-language immersion programme that is run at its branch at 223 Mountbatten Road.
The group piloted the programme for two nursery classes there three years ago. Classes including those on literacy, numeracy and arts are taught entirely in Mandarin.
Just a year into the programme, where Song Xuan and his peers would spend about six hours every day with a Mandarin-speaking teacher, Ms Wong says she could see a vast improvement. "Now, he talks to us in Mandarin about half the time at home.
He loves Mandarin pop songs and enjoys doing his Chinese homework. When we go to the library, he would want to borrow Chinese books."
Despite her apprehension about how he would take to the new school, Song Xuan showed no resistance from the beginning. Ms Wong says: "He loves going to school. A couple of weeks after he joined the school, he came back speaking some Mandarin and started to improve from there."
The Chinese-language immersion programme was so well received that EtonHouse plans to expand it to all pre-nursery and nursery classes at its new kindergarten at Hwa Chong International School, which is due to open on June 29.
SundayLife! found two schools, EtonHouse and Nanyang Kindergarten, which conduct programmes entirely in Mandarin The children in EtonHouse's Kindergarten 1 and 2 levels will move to a bilingual environment "to better prepare them for the primary school environment", says managing director Ng Gim Choo.
Ms Alice Tay, EtonHouse's Mandarin curriculum specialist, says the kindergarten programme is based on research on language learning in the early years, which shows that the immersion programme is best delivered 100 per cent in Mandarin. She adds: "Research has shown that the early years are a critical phase for children to develop second language skills."
Experts in this field here agree.
Associate Professor Lee Cher Leng, deputy head at the Department of Chinese Studies at the National University of Singapore, says the brain is wired in such a way that learning languages is most effective when one is young.
She adds that a full Mandarin immersion programme in preschool is recommended because of Singapore's "very English" environment where, since 1987, English has become the main language of instruction in schools here, with Chinese being taught as a subject.
So why are there not more full preschool programmes conducted entirely in a language other than English?
Some preschools, such as Two by Two Schoolhouse and Newton Kindergarten, conduct their programmes in Mandarin for between 60 and 80 per cent of the curriculum. This is due to their target demographic of children from English-speaking homes.
Another reason could be that children from non-English-speaking homes need help in preschool before going on to primary school, where the main language is English.
Associate Professor Mukhlis Abu Bakar, from the Asian Languages and Cultures Academic Group at the National Institute of Education, says a full immersion programme might be useful to balance the exposure to English that Singaporean children encounter daily.
There is a caveat: He believes the programme should not be extended into the kindergarten years.
He says: "With the English requirement looming at Primary 1, children, particularly those from non- English-speaking homes, will benefit from English literacy instruction in kindergarten."
At Two by Two Schoolhouse, playgroup children are exposed to Mandarin about 80 per cent of the time.
Director Li-Anne Sia says she did not opt for 100 per cent Mandarin as she feels parents would be more comfortable if there is an element of English in the curriculum. "Also, we don't want to put the children off learning Mandarin," she adds.
Almost all the children in her school are from English-speaking families, with 40 per cent of them being expatriates.
But she says that as the children become more proficient in the language and to better prepare them for primary school, their exposure to Mandarin is slowly reduced to about 60 per cent in Kindergarten 2.
British housewife Fiona Ratz, who is in her 40s, says Two by Two's programme has helped her daughter to do well in both Chinese and English in primary school.
Her seven-year-old, now in Primary 2, scored 90 per cent in Chinese at the end of Primary 1, just five percentage points lower than in English.
Legal counsel Henry Cheam's three daughters, aged three to eight, were or are enrolled at Newton Kindergarten, where about 60 per cent of the classes from playgroup to kindergarten are taught in Mandarin.
His oldest daughter, now in Primary 2, is doing well in Chinese and has no need for tuition.
Mr Cheam, 44, says: "I wouldn't be comfortable with a 100 per cent Mandarin curriculum. English is still the main language here.
Although we speak English to them at home, they still need to learn it formally in school from an early age."
Prof Lee says most children, even if they come from an English-speaking background, will have no problems adjusting to a full Mandarin curriculum in preschool.
"In preschools, languages are often taught through a fun activity that children are attracted to."
In fact, studies also show that a full immersion programme does not cause children to be less proficient in the socially dominant language.
For instance, a study by McGill University in Montreal, Canada, found that Anglophone children who completed a French immersion programme often turned out to be more proficient in English compared with their peers in English-medium schools.
But an early Chinese immersion programme is no guarantee the child will continue to like the language.
Javed Kesavan, a Primary 2 pupil, used to love Chinese at Two by Two Schoolhouse. When he entered primary school, he found the study of Chinese more mundane and is starting to dislike it.
His mother Pearly Yap, a fund manager in her 40s, says: "We plan to take him to Chinese camps in Taiwan, for instance, where there is a more natural environment for learning the language."
The solution to get children to like learning Chinese or their mother tongue more may be closer to home. Prof Lee advises parents to find something that interests them, be it a story book or an activity such as wushu.
Prof Mukhlis says parents should make more effort to interact with their children and read them stories in the mother tongue. He says: "Young children take their cues from their parents. If parents make the effort, they can gradually come around."
This article was first published on May 3, 2015.
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