에서 versus 에서는

[jsehl]

Okay, so I'm reasonably informed about the differences between 에 and 에서 (it appears to be one of the more common grammar questions out there), but I've never seen a written description of when to use 에서 versus 에서는 (hopefully because it's so simple??). I know that the 는 is a subject marker and thus signifies that the location is the subject, but I can't really see the difference when I see sentences that just have 에서.

Here's a correction that a grader put on an assignment I had once:
교실 안에서 먹으면 안돼요.
교실 안에서는 담배를 피우면 안돼요.

The best guess I can make is that in the second sentence the location is immediately followed by a noun whereas in the first it is followed by a (conjugated) verb? This one is especially difficult for a native English person to understand since translating it to "eating" and "smoking" makes it the exact same part of speech.

My guess is that this is so simple that it's not even worth discussing in most lessons on Korean grammar? I dunno, maybe it's something that I just didn't pick up because of my somewhat oddly formatted education in the language. Can anyone help?

Thanks.

 

[terredepomme]

I know that the 는 is a subject marker

는(은) is not a subject marker but a "thematic" marker. It can be used after a subject, an object, etc.
교실 안에서 담배를 피우면 안돼요.
You can't smoke inside the classroom.
교실 안에서는 담배를 피우면 안돼요.
You can't smoke inside the classroom.(Maybe you can smoke elsewhere?)
Inside the classroom, you can't smoke.
교실 안에서 담배는 피우면 안돼요.
You can't smoke cigarettes inside the classroom.(Maybe you can smoke something else? Or maybe you can drink but not smoke?)

Now these are subtle differences of nuance that one must learn by practice.
The first two cases can be used almost interchangeably. But the second emphasizes the element "교실 안에서," making it an important theme of the sentence.

 

[jsehl]

Ah, okay. If it's a nuance issue I can at least accept that it's an understanding-over-time kind of thing. The way that the grader wrote it on my paper, though, made it seem like one version was grammatically unacceptable (rather than one version having a different nuance).

Thanks!

 

[chingoo]

교실 안에서 먹으면 안돼요.
~에서 is used here as Prepositional particle for nominative. It is usually placed after a place noun(교실, 한국, 집, 서울 etc.)
This sentence implies that we generally know that foods are not allowed in the classroom.

교실 안에서는 먹으면 안돼요. (밖에서는 먹어도 돼요.)==> we can all guess that the latter sentence is omitted.
~에서+는 = prepositional particle for nominative + topic marker (it is used after a noun and it shows that noun is the topic of the sentence. The topic marker '는' here is used as contrast and emphasis.) This sentence implies that we can't eat in the classroom, (but you can eat outside so, go out to eat.)

You can judge which one to use in the context of the situation.

For example,
When a class begins for the first day, you want to talk about the class rule that the foods are not allowed to consume in the classroom, in that case you use '안에서',

If you use '안에서는' in that situation, it will be awkward because you emphasize on the negative fact to the people who you meet for the first time. I will use '안에서는' when I had caught someone eating in the classroom.

 

[Tomato potato]

Additional comment/opinion to chingoo's posting:
When the classroom rule is told, '안에서는' does not become awkaward if you want to imply that the rule does not need to be kept outside classroom.