Ten artykuł ma ciekawy nagłówek, ale sam tekst jest dłuższy, niż myślałam.

Because artykuł is a masculine singular noun, and ten is the masculine singular form of this.

Polish this changes by gender:

• ten for masculine nouns
• ta for feminine nouns
• to for neuter nouns

So:

• ten artykuł = this article
• ta książka = this book
• to zdjęcie = this photo

The demonstrative has to agree with the noun in gender, number, and case.

Because nagłówek is the direct object of ma (has), so it is in the accusative case. However, for many masculine inanimate nouns in Polish, the accusative singular looks exactly like the nominative singular.

So:

• nominative: ciekawy nagłówek
• accusative: ciekawy nagłówek

That is why the form does not visibly change here.

The adjective ciekawy also agrees with nagłówek:

• masculine
• singular
• accusative (same form here as nominative)

If the object were feminine, you would see a clearer change:

• mam ciekawą książkę = I have an interesting book

Nagłówek means headline or heading.

In this sentence, because the noun is artykuł (article), the most natural meaning is headline.

So:

• Ten artykuł ma ciekawy nagłówek = This article has an interesting headline

In other contexts, nagłówek can also mean a heading in a document, email, or form.

Here sam means something like:

• the text itself
• the actual text
• the text on its own

It adds emphasis and contrast.

So the sentence is not just saying:

• but the text is longer than I thought

It is more like:

• but the text itself is longer than I thought
• but the actual body of the text is longer than I thought

This contrasts the headline with the text itself.

Because tekst is a masculine singular noun in the nominative, and sam must agree with it.

Agreement here is:

• sam — masculine singular
• tekst — masculine singular

Compare:

• sam tekst = masculine
• sama książka = feminine
• samo zdanie = neuter

So the form sam is simply the correct masculine singular form.

Because tekst is the subject of the second clause:

• sam tekst jest dłuższy

The verb jest (is) needs a subject in the nominative.

So:

• sam tekst = subject, nominative
• jest dłuższy = predicate

This is different from nagłówek earlier, which is the object of ma.

Yes. Dłuższy is the comparative form of długi (long).

• długi = long
• dłuższy = longer

Polish often forms comparatives in one word, rather than using a separate word like more.

Examples:

• mały → mniejszy = small → smaller
• krótki → krótszy = short → shorter
• długi → dłuższy = long → longer

So:

• tekst jest dłuższy = the text is longer

Because the adjective must agree with tekst, which is masculine singular.

So the masculine singular form is:

• dłuższy

Compare:

• tekst jest dłuższy = masculine
• książka jest dłuższa = feminine
• zdanie jest dłuższe = neuter

This is standard adjective agreement in Polish.

Niż means than in comparisons.

So:

• dłuższy niż myślałam = longer than I thought

In Polish, niż is commonly used after comparatives like:

• większy niż = bigger than
• mniejszy niż = smaller than
• lepszy niż = better than

Here it introduces a whole clause:

• niż myślałam = than I thought

Usually no, not in this exact sentence.

Both niż and od can appear in comparisons, but they are used differently.

You can say:

• Jest dłuższy niż tamten tekst.
• Jest dłuższy od tamtego tekstu.
• It is longer than that text.

But when what follows is a clause like I thought, Polish uses niż:

• dłuższy, niż myślałam

Not:

• dłuższy od myślałam ❌

So niż is the correct choice because it means than I thought, not than something/someone.

Because the meaning is than I thought, which refers to what the speaker thought earlier.

• myślę = I think
• myślałam = I thought (female speaker)
• myślałem = I thought (male speaker)

The sentence compares the text's actual length with the speaker’s earlier expectation.

Because Polish past-tense forms show the gender of the speaker in the singular.

• myślałam = I thought said by a woman
• myślałem = I thought said by a man

So this sentence tells us that the speaker is female.

If a male speaker said the same thing, it would be:

• Ten artykuł ma ciekawy nagłówek, ale sam tekst jest dłuższy, niż myślałem.

Because Polish usually omits subject pronouns when they are not needed.

The verb form itself already tells you the person:

• myślałam = I thought (female speaker)
• myślałem = I thought (male speaker)

So ja is unnecessary unless you want extra emphasis or contrast.

Polish commonly drops pronouns like:

• myślę instead of ja myślę
• wiem instead of ja wiem

Because ale means but, and in Polish it normally introduces a new clause, so it is preceded by a comma.

Here we have two parts:

• Ten artykuł ma ciekawy nagłówek
• ale sam tekst jest dłuższy, niż myślałam

Polish punctuation regularly uses a comma before conjunctions like ale when joining clauses.

Because niż myślałam functions as a subordinate clause: than I thought.

So the comma separates the main part:

• sam tekst jest dłuższy

from the comparison clause:

• niż myślałam

This is very natural in Polish when niż introduces a full clause.

They are related, but not identical here.

• artykuł = the article as a whole
• tekst = the actual written content/body text

So the sentence contrasts:

• the article’s headline with
• the text itself

That is why sam tekst makes sense: the headline is interesting, but the actual body of the article is longer than expected.

Yes, Polish word order is fairly flexible, but this version sounds natural and highlights the contrast well.

• ale sam tekst jest dłuższy emphasizes the text itself
• ale tekst sam jest dłuższy is much less natural here
• ale dłuższy jest sam tekst is possible, but more marked or stylistic

The chosen order is standard and clear:

• ale = introduces contrast
• sam tekst = what is being contrasted with the headline
• jest dłuższy = what is being said about it

Here it most naturally means longer in content or longer to read, not physically longer on paper.

With tekst, Polish commonly uses długi / dłuższy to talk about how long a text is.

So:

• krótki tekst = a short text
• długi tekst = a long text
• tekst jest dłuższy, niż myślałam = the text is longer than I thought

It is the normal way to describe the length of written material.