Hello from Freiburg, Germany!

你好！
Welcome to the zoo!

We are a family that aimed for native level fluency and literacy in English, French and Mandarin (we are a Singaporean, French and Canadian rojak mix lol). All other languages are entirely up to the kids, who are now 17 and 10.

Your strategy of OPOL sounds ideal in your setup. Between the two of you, as you are both Singaporeans, may I suggest that you use Mandarin (if your husband is also a Mandarin speaker), all the way through to basic literacy? To set the stage for good Mandarin learning for the longer term when the literacy process starts? 

I suggest this based on our anecdotal experience and that of friends and acquaintances. We have all found that it helps, when there is a combination of languages that includes Mandarin as a minority language, for Mandarin to be much stronger than English (followed by German in your case) up to the time the child is in second grade. (One parent even suggested up to fourth grade; his teen girls are now extremely strong, balanced English/Mandarin bilinguals in US because he let English, the majority language, flounder a bit until the end of 4th grade and he chose to homeschool them until then. But how many parents are willing to live through that?)

My point is: The general consensus is that in such a context with Mandarin as a minority language, keeping the gap between it and the other languages as large as possible for as long as is possible helps the child remain motivated longer, and gives Mandarin a chance to grow together with the other languages because...

A) Simplified Mandarin doesn't have phonetic logic to it (I assume you will be doing simplified and not traditional). Once the children understand the phonetic logic of English and German, they are going to zoom by, decoding each new word more easily and more independently, thus increasing their confidence. With simplified, they are going to have to memorize each new radical and character (which means approx 3000-4000 characters give or take for functional literacy depending whom you ask). It also means the child isn't going to be able to decipher any new word by himself if there is a previously unseen (or unretained) radical or character. I know of at least 3 families in the US who even have their (bilingual) kids enter first grade knowing how to read up to 500 characters in Mandarin, with the aim of native level grade 6 (i.e. relative to Taiwan/China/Singapore kids) by the time they graduate from high school.

B) Mandarin requires the use of auditory (tones), vocal (tones) and muscle (stroke order) memories once we get into the literary phase. Pinyin or bopomofo can help, but only up to a certain degree. Which means that when it comes to reading, retention of each new vocabulary word takes more time than it does for, say, English. Writing will require even more time in order for the muscle memory for each word to take root, and for long term retention. When the child has other languages and preoccupations, and isn't in an environment like Singapore where Mandarin is everywhere and its learning emphasized in school, we probably can't have them mindlessly writing out x characters y times. So the very nature of the beast doesn't help it stay interesting to many children when there are so many other things to do.

C) it is harder to find synergy between Mandarin and the other languages. My 10 yo girl started Spanish in September last year, and her command of the language one year on has already allowed her to finish reading a compilation of short stories written in Spanish for teens by various Spanish writers (laboriously in parts for vocabulary, but still). The teacher and I truly believe that this has happened because she has applied her understanding of syntax, grammar (and to a lesser extent vocabulary) from French (and a little from English) to her study of Spanish. While Mandarin goes along at its own pace.

So take her pleasure at being able to read books in Spanish one year on, the fact that she enjoys young adult novels and classics in French and English...and compare all that with the fact that even though she already knows roughly 900 characters in Mandarin, she isn't yet literate enough to independently read every Mandarin book she thinks might be interesting. Which would be less of an issue in a more Mandarin-rich environment, whereas in our family, my husband doesn't know Mandarin at all, and Mandarin has always been a minority language, which means that keeping interest level high is just that little bit more challenging.

What this has all meant for us in our journey to date: At specific points in their learning in either Mandarin or their other heritage languages, we have seen a decrease in motivation in the literacy process for Mandarin...because it is definitely a minority language outside of Singapore, China, Taiwan, maybe parts of South California (huge community)...because it is much much harder (if at all) to find other heritage children (if at all) at similar levels of verbal and literary fluency for any age group...because of the particularities of the language. Thankfully the motivation has always come back. In the case of my 10 yo, her Mandarin has improved tremendously this last year because I decoupled the reading from the writing, which has also helped her with her motivation level.

What about German? I made the assumption that you are in Germany for the foreseeable future. In which case, once the children start to go to school, and start to have a "social" life, it will get stronger because it is the dominant language of the external environment. We moved around a lot, but chose the French system for our children so that there was consistency, quality, and freed up more time for English and Mandarin at home (outside of homework). The children know I work in French but also know that they speak with me in English or Mandarin (they largely prefer English, although they will write little notes outlining any displeasure in Mandarin lol). This strategy has helped us tremendously in our journey to date.

Hope our experience helps a bit.

Serina xoxo