こども "が" ねて いますから


>   1. こども **が** ねて いますから、しずかに して ください。
>
>   2. こども **は** ねて いますから、しずかに して ください。
>
>

I know that the 2nd one is incorrect. But why? To my understanding, が is used
to emphasize the subject we can hear or see, while は is rather for emphasizing
the subject with description or judgement. So it seems that both are correct
to me.




As far as I know, it is usually never technically incorrect to replace one for
another, but the emphasis will be different and so will the meaning.

Using は in your example, would give me this impression.

> Maybe YOU are not sleeping, but THE KIDS are, so calm down!

With the が the emphasis on comparing the sleeping people and the non sleeping
people is gone, and it becomes much more like a factual statement, which is
usually what you wish to say.

> [just so you know] the kids are sleeping so please don't make too much sound

