system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can children learn two or more languages without mixing them while growing up?

Simply: I have a little sister, she's 3 years old.  Since I'm always watching some american/british series and tv shows (like Steven Universe), she's growing up watching those with me (we are brazilians, so she's growing listening and speaking mostly portuguese ~~and nonsense~~)

I couldn't help but notice that recently, she's noticing the differences between portuguese and english, for example, I'm watching something, then she comes and says:

"Ela disse 'ball' haha" (she said 'ball' haha)

or then

"Blue, why are you watching english?"

Sometimes I even ask things like: "Do you wanna listen to 'Let it Go' in english, or portuguese?" and she freaking understands the difference between both, and reply either "english" or "portuguese".

**How so?**
gpt
Young children are still at an age where they are learning language and the constructs of it. This makes it easier for them to acquire new language, because they can learn the ins and outs of both languages at fairly quickly. They're not "cemented" into one language yet. Their brains have a plasticity to them that make it easier to form new connections in contrast with an adult brain that isn't as moldable.


I teach 3 year olds, have several bilingual students, and one trilingual student. She has been slower on the uptake of language at all, because she gets the languages confused, but even in the last 3 months of school she's become more fluent in both English and Spanish (both of which are spoken at school). It's really amazing to see what a three year old's brain is capable of.