Na ploči nije podcrtano ništa osim infinitiva, pa učenici pitaju što trebaju zapisati.

Na ploči means on the board.

Croatian uses na + locative for many surfaces and places where something is located on something:

• na stolu = on the table
• na zidu = on the wall
• na ploči = on the board

Here ploči is the locative singular of ploča.

If you used u, it would usually mean in or inside, which does not fit here.

Ploči is locative singular.

The noun is:

• ploča = board

After na when it expresses location, Croatian uses the locative:

• na ploči = on the board

So:

• nominative: ploča
• locative: ploči

Nije podcrtano means is not underlined / has not been underlined.

It consists of:

• nije = is not / has not
• podcrtano = underlined

The form podcrtano is a past passive participle in the neuter singular.

In this sentence, it matches ništa, which is treated as neuter singular:

• ništa nije podcrtano = nothing is underlined

Even though the word order here is different:

• Nije podcrtano ništa... it is still the same basic structure.

Because of ništa.

Ništa means nothing, and in Croatian it behaves like a neuter singular word. So the participle also appears in neuter singular:

• ništa je podcrtano would be wrong because the negation is missing
• ništa nije podcrtano = correct

Compare:

• tekst je podcrtan = the text is underlined (masculine singular)
• rečenica je podcrtana = the sentence is underlined (feminine singular)
• ništa nije podcrtano = nothing is underlined (neuter singular)

Croatian word order is more flexible than English word order.

You could also say:

• Ništa nije podcrtano osim infinitiva.

That version may sound a bit more straightforward to an English speaker.

The original:

• Na ploči nije podcrtano ništa osim infinitiva is also natural. Putting ništa later can give slightly more focus to the statement as it unfolds.

So this is mostly a matter of word order and emphasis, not a change in meaning.

Because osim requires the genitive case.

So:

• infinitiv = nominative
• infinitiva = genitive

After osim (except / apart from), you normally use the genitive:

• osim mene = except me
• osim škole = except the school
• osim infinitiva = except the infinitive

Here osim means except.

So:

• ništa osim infinitiva = nothing except the infinitive

It can also mean apart from or besides, depending on context, but in this sentence except is the clearest meaning.

Here pa means something like:

• so
• and so
• therefore

It connects the two clauses:

• Na ploči nije podcrtano ništa osim infinitiva
• pa učenici pitaju što trebaju zapisati

So the idea is:

• nothing except the infinitive is underlined on the board,
• so the students ask what they should write down.

Croatian pa is very common and can have slightly different shades of meaning depending on context, such as and then, so, or well then.

Because pa is linking two clauses here.

The sentence has two parts:

1. Na ploči nije podcrtano ništa osim infinitiva
2. učenici pitaju što trebaju zapisati

When pa connects clauses like this, a comma is normally used:

• ..., pa ...

So the comma helps mark the clause boundary.

Učenici is nominative plural, because it is the subject of pitaju.

The basic noun is:

• učenik = student / pupil (male or mixed group in plural)

Plural nominative:

• učenici = students

Since they are the ones doing the asking, nominative is required.

Pitaju is the 3rd person plural form of pitati = to ask.

It agrees with učenici:

• učenici pitaju = the students ask

Compare:

• učenik pita = the student asks
• učenici pitaju = the students ask

Here što means what.

This is an indirect question:

• što trebaju zapisati = what they should write down

So što introduces the content of what the students are asking.

In standard Croatian, što is very common for what. In some varieties you may also hear šta, but što is the standard form.

Yes. It is a subordinate clause, specifically an indirect question.

Structure:

• što = what
• trebaju = they should / need to
• zapisati = write down

Together:

• što trebaju zapisati = what they should write down

It functions as the object of pitaju:

• učenici pitaju [što trebaju zapisati]

Trebaju zapisati means they should write down or they need to write down.

It contains:

• trebaju = they should / need to
• zapisati = to write down

Croatian often uses trebati + infinitive to express need or obligation:

• trebam učiti = I need to study
• trebaju zapisati = they need to write down

Depending on context, English might translate this as should, need to, or are supposed to.

Because zapisati is perfective, and here the action is seen as a single complete act: writing something down.

• zapisati = to write down, complete the act
• zapisivati = to be writing down / to write down repeatedly or habitually

In this sentence, the students are asking what exactly they are supposed to note down, so the perfective zapisati fits better.

• pisati = to write
• zapisati = to write down, note down

The prefix za- here gives the idea of recording something, making a note of it.

So:

• pisati is more general
• zapisati is more specific: write something down so it is recorded

That is why zapisati is natural in a classroom context.

Because Croatian has no articles.

English says:

• on the board
• the students
• the infinitive

Croatian simply uses the noun without an article:

• na ploči
• učenici
• infinitiva

Whether something means a, an, or the is understood from context.

Yes, absolutely.

That version is very natural and may feel more transparent to an English speaker:

• Ništa nije podcrtano osim infinitiva.

The original:

• Na ploči nije podcrtano ništa osim infinitiva adds the location first (on the board) and slightly shifts the emphasis.

Both are correct; the difference is mainly one of word order and focus.

Yes.

Podcrtano gives a passive idea:

• nije podcrtano = is not underlined / has not been underlined

The sentence does not say who failed to underline it. It only describes the result visible on the board.

That kind of passive-style expression is very common in Croatian.