Playtime in Mandarin
Try this at home, or in a controlled environment.
Around the same time I was panicking about the lack of a Chinese language environment in our area, a few neighborhood parents were looking for a way to supplement their soon-to-be 5-year-old's after-school activities with learning Mandarin. It's also around the same time I started introducing Mandarin to my semi-Canto-speaking toddler, who had just realized that different languages/forms of communication can coexist. Anyway, it was an easy “Yes, my kid and I would love to play with your kids in Mandarin.
I went into each gathering with a different theme / main takeaway for the day, focusing on colors one week, body parts the next, a relevant Chinese holiday whenever one's near, sports, weather, etc. Whether they were executed as planned or not, usually 40% not, I was serious about playtime…and play they did, in Mandarin. Everything we did, everything we read, everything we touched, was translated and repeated in Mandarin...employing many of the drilling techniques I picked up while working for Princeton in Beijing.
The children were pretty much zero beginners in Mandarin. Some are hapas like mine, some come from culturally diverse parents, some are seeking out cultural diversity. This is a weekly occurrence that lasts 1.5 hours, unfortunately not enough repetition for formal language learning, but sufficiently captivating for kids with short attention spans to keep wanting more. Playgroup size is no more than 5 each time, so each child can get some one-on-one interactions as well.
The structure varies based on the group's interests and energy level that day, so variations are very much expected, but usually involve these activities:
Drawing names: Basically roll call to learn common phrases like 你好！我叫___, 你呢？(Hi! My name is ____, and you?) 他的名字是___。(His name is____.) ____是她！(____is her!) 她在哪？(Where is she?) 他在那儿！(He's over there!)
Reviewing previously learned phrases,
Reading circle: Read any book aloud in Mandarin, regardless of original text language.
An activity to get them moving around while speaking Mandarin, like Hide & Seek.
Asian snack time: Introduce some snacks they normally would not be exposed to...but only AFTER they've learned to say what they're eating in Mandarin, how to ask for it 我要一个/两个/三个..., how to ask for more 我还要..., followed by 谢谢！(Thank you!)
Free play while listening to Chinese songs.
Coloring/drawing using my illustrations or simply doodling on a blank sheet of paper. Great opportunity to introduce phrases like 这个是什么颜色？(What' is this color?) 我最喜欢的是____。(May favorite color is _____.) 我也要用____。(I would also like to use ____.) 你用完了吗？(Are you done with that?)
So far, the dynamic has been great between the children, we learn with/from one another and are excited for playtime every week. This is something that most bilingual parents can do at home and schedule playdates for. Expert tip:
Make sure there aren't so many distractions that everybody ends up doing their own thing. If possible, limit the activities in the room to focus only on the things that the kids can do together.
Hope that helped!