Learn Hardcore Korean: seonsaengnimi naeil sueobi issdago malhaesseoyo. - The teacher said there is class tomorrow.

선생님이 is the subject of the main clause 말했어요.
수업이 is the subject inside the quoted (embedded) clause 있다고. Also, 이 vs 가 is chosen by sound: after a consonant use 이 (e.g., 선생님이, 수업이), after a vowel use 가 (e.g., 학교가).

Could I use 은/는 instead of 이 after 선생님?

You can, with a nuance change:

선생님이: neutral, introducing the teacher as the grammatical subject.
선생님은: makes “teacher” the topic; often used for contrast or when the teacher is already known in context. For extra respect, use the honorific subject marker: 선생님께서.

Why is it 있다고 and not 라고? When do I use -다고 vs -(이)라고?

It depends on what the quoted clause ends with:

Verbs and adjectives (descriptive words): use -다고. Ex: 온다고, 예쁘다고, 있다고, 없다고.
Nouns with the copula 이다: use -(이)라고. Ex: 학생이라고, 선생님이라고. In this sentence, 있다 is a descriptive/stative verb, so you get 있다고.

I learned verbs take -ㄴ/는다고. Why isn’t it 있는다고?

For present-tense action verbs you get -ㄴ/는다고 (e.g., 간다고, 먹는다고). But descriptive adjectives and stative verbs like 있다/없다 pattern with -다고 (not -는다고). So:

Action verb: 가다 → 간다고
Descriptive: 예쁘다 → 예쁘다고
Stative: 있다 → 있다고, 없다 → 없다고

Can I report this with direct speech instead of indirect?

Yes. Direct speech keeps the original sentence form inside and adds -라고:

Direct: 선생님이 내일 수업이 있어요라고 말했어요.
Indirect (your sentence): 선생님이 내일 수업이 있다고 말했어요. In writing, people often use quotation marks around the direct quote; in speech, prosody does the job. Indirect is more common and smoother in everyday narration.

Why is the inside clause present tense (있다고) when it’s about tomorrow?

Korean often uses present tense with a time word to express scheduled or set events. 내일 already places it in the future. If you want to explicitly sound predictive, use future:

Schedule/announcement feel: 내일 수업이 있다고 말했어요.
Prediction/expectation: 내일 수업이 있을 거라고 말했어요.

Does this mean the teacher has class, or that we have class?

Literally it’s “there is class,” which in context means class will be held. It doesn’t specify whose class. You can clarify:

We (students) have class: 우리(반)는 내일 수업이 있다고 말했어요.
The teacher will hold/teach class: 선생님이 내일 수업하신다고 말했어요.

Can I say 수업한다고 instead of 수업이 있다고?

You can, but the nuance shifts:

수업이 있다고: there will be a class (existence/schedule).
수업한다고: someone will conduct/do a class (an action). If the subject is the teacher, 선생님이 내일 수업한다고 말했어요 naturally means the teacher said they will hold class.

How do I say “The teacher told me (to me)”?

Add a recipient with -에게/-한테 (neutral) or -께 (honorific):

선생님이 저한테 내일 수업이 있다고 말했어요.
More respectful to the teacher: 선생님께서 저에게 내일 수업이 있다고 말씀하셨어요. To emphasize benefit to you, you can add -아/어 주다: 말해 줬어요.

How do I make the sentence more respectful toward the teacher?

Use honorific forms:

Subject particle: 선생님께서
Honorific verb and suffix: 말씀하시다 with -시-
Example: 선생님께서 내일 수업이 있다고 말씀하셨어요.

Is it rude to use 말했어요 for a teacher?

Not rude, but it’s plain. In formal or polite contexts, prefer the honorific:

말씀하셨어요 (instead of 말했어요).
With subject honorific: 선생님께서 … 말씀하셨어요.

Can I drop some particles in casual speech?

Yes, in conversation particles are often omitted:

선생님 내일 수업 있다고 말했어요. However, keep particles in careful writing or when clarity matters.

Is the word order fixed?

Flexible within limits. The quoted clause precedes the reporting verb, but you can move adverbs and subjects:

내일 선생님이 수업이 있다고 말했어요.
내일 수업이 있다고 선생님이 말했어요. All are natural; the meaning stays the same.

Is 말했어요 necessary? I often see …했다고 했어요.

You can use -다고 하다 without 말하다:

선생님이 내일 수업이 있다고 했어요. This is extremely common. 말했어요 is fine too; 하다고 했어요 is just lighter and more frequent in speech.

How do I report questions, commands, or suggestions instead of statements?

Use different quoting forms:

Question: …냐고 하다 (or 묻다/물어보다). Ex: 선생님이 내일 수업 있냐고 물어보셨어요.
Command/request: …(으)라고 하다. Ex: 내일 꼭 오라고 하셨어요.
Suggestion: …자고 하다. Ex: 내일 수업 준비 같이 하자고 하셨어요.

What about the hearsay/report suffix -대요 that I hear in speech?

It’s a conversational shortcut for indirect quotes:

선생님이 내일 수업이 있대요. = “They say/the teacher says there’s class tomorrow.” It’s natural in everyday talk; for careful writing or clear attribution, …있다고 했어요/말했어요 is safer.

Are there register alternatives for the final verb?

Yes, change the ending to match formality:

Formal polite: 말했습니다 / 말씀하셨습니다
Plain: 말했다 / 말씀하셨다
Casual spoken: 말했어요 / 말씀하셨어요