から at the end of a sentence

Hello,

When a sentence ends in から it means that what follows after that is omitted and should be easily understood from context, right? Can you check if I am getting the meaning of the following sentences right, please?

1) ２年６組。ここが、きみのクラスだから。
動画の再生｜基本スキット｜第1課 (the sentences is around the beginning, before the teacher enters the classroom)

What would be the continuation for this sentence? ここが、きみのクラスだから入りましょう ?

2) ここが図書室。放課後は６時まで開いてるから。貸し出しもしてるよ。
動画の再生｜基本スキット｜第2課 (when they first enter the library. At the middle of the video)
Is she saying something like "After school, it is open until 6 o'clock, so if you need the library come before 6"?

3) ほんと、おおげさなんだから。
動画の再生｜応用スキット｜第2課 (at the end of the video, right before it shows けんた eating)
I can tell that she is means something negative with this から. Something like "He really exaggerates, that is why I didn't want to trade"? or "that is why he annoys me"?

4) Finally, I felt like reading よつばと again today and found a similar sentence.
ちなみに燃えるゴミは月木 燃えないゴミは土曜日ですから
(first image for context. the sentence is in the second image, first panel)
http://s29.postimg.org/mekvke41j/0020.jpg
http://s29.postimg.org/gg72a5l2v/0021.jpg

"By the way, for the burnable trash, it is Monday and Thursday. The non-burnable trash is Saturday. So please respect this schedule." Is this close to what would follow after から?

から at the end of a sentence doesn't always explain the reason/cause. Especially, #1 wouldn't be the reason. It's said から has a function that the speaker gives information for the addressee to change their(=the addressee's) action/thoughts. See the following examples.

A: ゴメン。本当にすまなかった。
B: そんなに謝らなくてもいいから。

ちょっとお金貸してくんない？1000円でいいからさ。
（＝1000円でいいからお金貸してくんない？）

In these examples, the clause/phrase preceding から is not the reason/cause of the speaker's action. The reason would be 怒ってないから and お金がないから/買いたいものがあるから, respectively. The speaker suggests the addressee to change their thoughts in the former example, and to do an action (to lend 1000yen) in the latter. The nuance is often close to よ in these cases.

ここが、きみのクラスだよ。
放課後は６時まで開いてるよ。貸し出しもしてるし。
そんなに謝らなくてもいいよ。

～の/んだから has different nuances from just から. When it's said to the addressee face to face, the preceding clause/phrase is always what the addressee already knows, and often has a nuance of blame.

ここは病院なんだから、静かにしなさい！
In this example, the addressee clearly recognizes they are in a hospital now and they have to be quiet there. The speaker expressly points it out, therefore this expression has a nuance of blame.
As for your example #3, she said it to herself. If it's said to him, it's blame to him.

raikado said:

What would be the continuation for this sentence? ここが、きみのクラスだから入りましょう ?

Click to expand...

If it were me, I'd infer something like, きみのクラスだから（覚えておいてね）. This is your classroom (remember where it is).

But, I'm not sure it's worth the effort to infer anything beyond the から in sentences like this. For example, if I were to translate the sentence above, I'd just leave it as "This is your classroom." Sure, there's an implication that something is left unsaid, but without any other situational clues (e.g. the person went into the wrong classroom first, and is now being guided to their correct classroom), then it would be a guess (maybe an educated guess, but still a guess) as to what was being implied by the speaker.

Thinking about it, this use of から is almost like a flag for the listener to "file this info away for the future."

から［副接頭］の意味 - 国語辞書 - goo辞書
［接助］活用語の終止形に付く。
２ （終助詞的に用いて）強い主張、決意を表す。ぞ。「思い知らせてやる―」

Indeed that is one of the functions of から as a sentence final particle, but it doesn't apply to the examples raikado-san provided. Here's an example of strong assertion/determination.

間違った説明には絶対惑わされないからな！

A linguist 白川博之 wrote an article 『理由を表さない「から」』 in a book 複文の研究（上）, if you interested in this topic.
Amazon product ASIN 4874241042

Thank you everyone! I understand how this works now.

One more question about んだから. My example ends in んだから, with no continuation. Is this like a sentence-ending particle as well? (In other words, she doesn't simply omit the conclusion as I assumed originally, right?)

んだから has same meaning as のだから where の is the "explanatory no" that you're probably familiar with. And だ・です is the copula. I think your understanding was correct. There is something left unsaid that is implied.

Unlike (なの)よ, なんだから has a "softening" effect because of "saying to herself" there. The function would be to give an information to the listener.

Umm, I'd like to clarify this "saying to herself".

So, if she would've said ほんと、おおげさなんだから straight to him, it would mean "You know you really exaggerate...". "You know" coming from んだから.
When she says that sentence to herself does she say "He knows he really exaggerates..."? Which would mean that the blame is still towards him, but it is not said straight to him.

I know you said "As for your example #3, she said it to herself. If it's said to him, it's blame to him." but what I understand from this is "she says it to herself therefore the blame is towards herself", which doesn't seem to fit with the text.

The blame is not to herself. It's still for him, but the main purpose is to give the information to the listener(s) indirectly (since it's said toward herself, not toward the listener(s) directly). The softened tone is from this "indirectness".

I see. I get it now. Thank you!