Learn Hardcore Greek: Η αδερφή μου λέει ότι ο βαθμός της ήταν άδικος, αλλά ο δάσκαλος πιστεύει ότι ήταν δίκαιος. - My sister says that her grade was unfair, but the teacher believes it was fair.

λέει describes what she is doing now (she is saying/claiming this now),
while ήταν describes the time of the event (the grade was given in the past, the unfairness relates to that past grading).

English does exactly the same:
My sister *says that her grade was unfair.*

If you wanted to place the whole thing firmly in the past, you could also say:

Η αδερφή μου είπε ότι ο βαθμός της ήταν άδικος.
My sister said that her grade was unfair.

Could we say είναι άδικος instead of ήταν άδικος? What is the difference?

Yes, you can say είναι άδικος, but the nuance changes slightly.

ήταν άδικος (was unfair)
Focuses on the past grading event. The grade was given, and that act of grading was unfair.
είναι άδικος (is unfair)
Focuses more on her opinion about the grade now, as a current state.

In practice:

Ο βαθμός της ήταν άδικος.
Sounds like: “The way she was graded was unfair.”
Ο βαθμός της είναι άδικος.
Sounds more like: “That grade (as it stands now on the paper/report) is unfair.”

Both are grammatically correct; context and speaker preference decide which one fits better.

What exactly does βαθμός mean here? Is it “grade”, “mark”, or “score”?

In this context, ο βαθμός means “grade/mark” (the number or letter you receive in school).

Depending on context, βαθμός can mean:

school grade/mark:
- Ποιος είναι ο βαθμός σου στα Μαθηματικά;
  What’s your grade in Math?
degree/level (more abstract):
- υψηλός βαθμός δυσκολίας – a high degree of difficulty

Here, because we have ο δάσκαλος and the idea of fairness, it clearly refers to a school grade.

Why are the adjectives άδικος and δίκαιος in the masculine form?

Adjectives in Greek agree in gender, number, and case with the noun they describe.

ο βαθμός is:
- masculine
- singular
- nominative

So the adjectives must also be:

άδικος – masculine singular nominative
δίκαιος – masculine singular nominative

That’s why we say:

ο βαθμός της ήταν άδικος
ο βαθμός (του) ήταν δίκαιος

If the noun were feminine, the adjectives would change:

η απόφαση ήταν άδικη / δίκαιη
(the decision was unfair / fair)

And if neuter:

το σύστημα ήταν άδικο / δίκαιο
(the system was unfair / fair)

Why is it ο βαθμός της and not της βαθμός? How do possessive pronouns work here?

In Greek, the usual pattern with weak possessive pronouns (μου, σου, του, της, μας, σας, τους) is:

article + noun + possessive pronoun

So:

ο βαθμός της = her grade
η αδερφή μου = my sister
το βιβλίο σου = your book

Saying της βαθμός is wrong in standard Greek.

You can move the possessive in some emphatic or special structures using δικός/δική/δικό:

ο δικός της βαθμός – her own grade (emphasis on “her”)
η δική μου αδερφή – my sister, not someone else’s

But with the simple weak pronoun, it always comes after the noun, not before.

What exactly does της refer to in ο βαθμός της? Is it the sister?

Yes. In this sentence, της refers back to η αδερφή μου.

Η αδερφή μου λέει ότι ο βαθμός της ήταν άδικος…
My sister says that *her grade was unfair…*

Because the only obvious feminine referent in the context is η αδερφή μου, της naturally refers to my sister.

If there were more feminine nouns in the larger context, you’d rely on context or add more words:

ο βαθμός της αδερφής μου – my sister’s grade
ο βαθμός της Μαρίας – Maria’s grade

But in the given sentence, της alone is clear enough.

Why is it Η αδερφή μου and not just Αδερφή μου without the article?

Greek uses the definite article much more than English, especially:

with family members
with possessive pronouns

Standard pattern is:

η αδερφή μου – my sister
ο πατέρας μου – my father
η μητέρα σου – your mother

Saying αδερφή μου without the article is possible, but:

it sounds more poetic, emotional, or informal, e.g. in songs or direct address:
- Αδερφή μου, σε αγαπώ. – My sister, I love you. (vocative feel)
in ordinary narrative speech (§ like our sentence), η αδερφή μου is the normal, neutral form.

I’ve seen αδελφή with an λ instead of αδερφή. Is there a difference?

Both forms refer to the same thing: sister.

αδελφή – more formal / closer to the older, “official” spelling
αδερφή – more colloquial / everyday Demotic Greek spelling

In modern usage:

You’ll see αδελφή in more formal texts, religious texts, or spelling-conscious writing.
You’ll hear and see αδερφή very commonly in everyday speech and informal writing.

In spoken Greek, they are pronounced almost the same; speakers switch between them without any change in meaning.

What does λέει ότι mean exactly? Is it like “says that” in English?

Yes. λέει ότι literally means “(she) says that”.

λέει – he/she says (3rd person singular, present tense of λέω)
ότι – introduces a content clause, like English that:

Examples:

Λέει ότι δεν έχει χρόνο.
He/She says (that) he/she doesn’t have time.
Λένε ότι θα βρέξει.
They say (that) it will rain.

You can often omit that in English, but in Greek you generally keep ότι (or πως) in standard speech:
Λέει (ότι) δεν έχει χρόνο is also heard, but in careful language ότι is preferred.

What is the difference between ότι and πως here? Could we say λέει πως ο βαθμός της ήταν άδικος?

Yes, you can also say:

Η αδερφή μου λέει πως ο βαθμός της ήταν άδικος…

In this use, ότι and πως both introduce a “that-clause” and are usually interchangeable:

λέει ότι…
λέει πως…

The main differences:

ότι is a bit more formal / neutral, very common in writing.
πως is slightly more conversational, very common in speech.

Important: ότι (no comma) is different from ό,τι (with comma), which means “whatever / anything that”:

Ξέρω ότι έχεις δίκιο. – I know (that) you are right.
Πάρε ό,τι θέλεις. – Take whatever you want.

Why doesn’t the second clause repeat ο βαθμός της? How do we know what ήταν δίκαιος refers to?

Greek often omits repeated words when the reference is clear from context. In the sentence:

…αλλά ο δάσκαλος πιστεύει ότι ήταν δίκαιος.

The subject of ήταν δίκαιος is understood to be ο βαθμός της from the previous clause.

You could explicitly repeat it:

…αλλά ο δάσκαλος πιστεύει ότι ο βαθμός της ήταν δίκαιος.

Both versions are correct; the shorter one avoids unnecessary repetition. Greek does this a lot with:

implied subjects (dropping αυτός/αυτή/αυτό)
implied objects
nouns already mentioned

Context and agreement (here: δίκαιος masculine singular matching ο βαθμός) make the reference clear.

What does αλλά do here? Could we use something like όμως instead?

αλλά is a coordinating conjunction meaning “but”. It introduces a contrast:

…ήταν άδικος, αλλά ο δάσκαλος πιστεύει ότι ήταν δίκαιος.
…was unfair, but the teacher believes it was fair.

You can also use όμως (however/but), but it behaves more like an adverb and can move position:

…ήταν άδικος, όμως ο δάσκαλος πιστεύει ότι ήταν δίκαιος.
…ήταν άδικος. Ο δάσκαλος όμως πιστεύει ότι ήταν δίκαιος.

So:

αλλά = fixed connector between two clauses (but)
όμως = more flexible (however / though), can appear after the subject or at the start of the clause.

Why is μου placed after αδερφή in Η αδερφή μου? Can it go before?

The weak possessive pronoun μου normally comes after the noun:

η αδερφή μου – my sister
ο φίλος μου – my friend
το σπίτι μου – my house

You do not say μου αδερφή in standard Greek.

If you want to emphasize possession, you use δικός/δική/δικό:

η δική μου αδερφή – my sister (as opposed to someone else’s)
ο δικός μου φίλος – my friend

But the basic rule is:

article + noun + weak possessive
η αδερφή μου, ο βαθμός της, το βιβλίο σου

What is the difference between λέει and πιστεύει in this sentence?

They describe two different things:

λέει – she says / she claims
- Focus on what she expresses verbally.
πιστεύει – he believes / he thinks (deeply)
- Focus on the teacher’s inner conviction/opinion.

So:

Η αδερφή μου λέει ότι ο βαθμός της ήταν άδικος…
She states/claims it was unfair.
…αλλά ο δάσκαλος πιστεύει ότι ήταν δίκαιος.
The teacher believes it was fair (what he considers true).

You could also say νομίζει (thinks / believes, but usually with less weight) instead of πιστεύει, but πιστεύει often sounds a bit stronger or more assured.