Experts in bilingualism all say you need to follow the one parent one language rule. There may be truth to it, but I think that is not enough exposure to fully learn a language that is not dominant in your environment.
We moved away from our ‘home’ language country when I was 10. My mom always made the effort to speak to us in her language. What else could she have spoken since her English was not that strong. I really really hated that she would do that. One day walking home from school I just ran around the block just to avoid being greeted by her in our native language in front of my friends.

The bilingualism advocates are aggressive, to the point of almost brandishing the kid who refuses to speak language 2 as an evil traitor
I came across someone advocating totally refusing to speak to a child unless they speak to you in your language. Apparently that worked with someone whose kid was force fed this for 6 months.
Nobody though of advising you to talk with children, no matter what, and regardless of what language that happens to be in

Does not seem rude or strange to me.

Anonymous wrote:She was probably reprimanding her kid and did it in their language to help the kid save face, or didn’t know the English words, or forgot, etc. let it go .

Not reprimanding. Just regular talking.

It would be rude in my culture as well. Does mom only speak to kid in her native tongue (this is common with families who are trying to teach kids their native language), maybe she just forgot. If her norm is to speak to her kid in French for example, it feels weird to speak to them in a different language--even one you are both fluent in.

Anonymous wrote:I think "rude" is too harsh. It probably doesn't occur to her to do anything else since that's always how she speaks to her kid. Clueless to more considerate behavior is how I would see that.

I also don't see why you have to know what she is saying to her kid. Sure, it would be nice, but not entirely necessary.

That's sort of the definition of rude

In our culture, it is rude

I have a friend who does this. It never occurred to me to be upset. It’s not like she’s talking about us.

Yes it’s rude

You are a psycho OP

Not rude in the slightest.

Good lord op

She was probably reprimanding her kid and did it in their language to help the kid save face, or didn’t know the English words, or forgot, etc. let it go .

Get over it Op. It is nor a big deal.

I think "rude" is too harsh. It probably doesn't occur to her to do anything else since that's always how she speaks to her kid. Clueless to more considerate behavior is how I would see that.

I also don't see why you have to know what she is saying to her kid. Sure, it would be nice, but not entirely necessary.

This happened during a one-on-one play date yesterday and I found it rude. Convince me otherwise.

We are bilingual too so I get it. I speak to my child in our other language exclusively when we are at home, with family or in public (somewhere we are not really interacting with others). But if it is a one-on-one situation I can’t imagine speaking to my child 80% of the time in a language that the other family doesn’t understand.