Learn Hardcore Croatian: Na jednoj platformi znanstvenica drži online‑predavanje o svemiru umjesto radionice u učionici, koje bilo tko može pratiti bilo gdje u svijetu. - On one platform the scientist female gives an online lecture about space instead of a workshop in the classroom, which anyone can follow anywhere in the world.

The preposition na (on) + a location normally requires the locative case.
platforma is feminine singular.
- Nominative (dictionary form): jedna platforma
- Locative: jednoj platformi

So:

jedna platforma = nominative, used for the subject (A platform is new.)
na jednoj platformi = locative, after na when it means on / at a place.

That is why both the adjective jednoj and the noun platformi are in the locative case.

What nuance does na jednoj platformi have? Why jednoj instead of just na platformi?

na jednoj platformi literally means on one platform and usually implies:

some unspecified platform, one of many, not important which one
the speaker doesn’t want or need to name it

If you said na platformi without jednoj, it would sound more like:

on the platform (already known from context), or
on a specific, context‑given platform

English often doesn’t mark this difference clearly, but Croatian can show this nuance with jedan / jedna / jedno.

Why znanstvenica and not znanstvenik?

Croatian increasingly uses explicit feminine forms for professions.

znanstvenik = male scientist, or traditionally a generic form
znanstvenica = female scientist

Since the sentence is clearly about a woman, it uses znanstvenica. Both forms are common, but using the feminine form when the person is female is standard and natural in modern Croatian.

What does drži online‑predavanje literally mean? Why use držati here?

The verb držati literally means to hold (physically). But in Croatian it is very commonly used in academic / formal contexts:

držati predavanje = to give a lecture
držati govor = to give a speech
držati tečaj = to run a course

So znanstvenica drži online‑predavanje = the scientist is giving an online lecture.

You could also say:

održava online‑predavanje (very natural, maybe a bit more formal)
ima online‑predavanje (more colloquial)

But držati / održati predavanje is the standard collocation.

Is the hyphen in online‑predavanje necessary? Can I say online predavanje?

In practice, both are used:

online predavanje – very common and perfectly acceptable
online‑predavanje – sometimes used to show that online functions like a bound prefix

Official spelling recommendations often prefer writing such foreign prefixes together (e.g. online predavanje or online‑predavanje, or even onlinepredavanje), but in everyday writing online predavanje (two words, no hyphen) is probably the most frequent and absolutely fine.

So yes, you can safely say online predavanje.

Why is it o svemiru and not something like o svemir?

The preposition o (about) requires the locative case in standard Croatian.

Nominative: svemir (universe)
Locative: o svemiru (about the universe)

So:

pričamo o svemiru = we talk about the universe
članak o svemiru = an article about the universe

Using nominative o svemir would be ungrammatical.

Why is radionice in that form after umjesto?

The preposition umjesto (instead of) governs the genitive case.

Nominative: radionica (a workshop)
Genitive singular: radionice

Therefore:

umjesto radionice = instead of a workshop
umjesto učionice = instead of the classroom
umjesto predavanja (gen. of predavanje) = instead of a lecture

In the sentence, umjesto radionice u učionici means instead of a workshop in a classroom.

Why is u učionici in that form?

The preposition u (in) with a static location usually takes the locative case.

Nominative: učionica (classroom)
Locative: u učionici (in the classroom)

So:

u učionici = in the classroom
u školi = in the school
u kući = in the house

Together with umjesto radionice u učionici, the meaning is: instead of a workshop that would take place in a classroom.

Why is the relative pronoun koje and not koju or koja?

The relative pronoun must agree in gender and number with its antecedent, and in case with its role in the relative clause.

Antecedent: online‑predavanje
- gender: neuter
- number: singular
In the relative clause koje bilo tko može pratiti, the pronoun is the direct object of pratiti, so it must be in accusative.

Neuter singular forms:

Nominative: koje
Accusative: koje (same form)

So koje is correct for neuter singular as object.

koja would be used with a feminine noun (e.g. radionica koja...)
koju would be feminine accusative singular (e.g. radionicu koju bilo tko može pratiti)

Why is there a comma before koje? Is the clause restrictive or non‑restrictive?

The comma before koje introduces a relative clause:

...umjesto radionice u učionici, koje bilo tko može pratiti bilo gdje u svijetu.

This clause gives additional information about the online lecture (that anyone can follow it anywhere in the world), not something that distinguishes it from other possible online lectures. So it is non‑restrictive.

In Croatian, non‑restrictive relative clauses are normally separated by a comma, just like in English:

The scientist gives an online lecture, which anyone can follow…

If it were a restrictive clause (picking out which lecture we mean), you would still usually use a comma in writing, but context and intonation would differ. Here the intent is clearly extra information.

What does bilo tko mean, and how is it different from svatko, netko, and itko?

bilo tko literally means anyone at all. It is an indefinite pronoun often used with a sense of no restriction:

bilo tko može pratiti = anyone (at all) can follow

Comparison:

svatko = everyone
- svatko može pratiti = everyone can follow (each person)
netko = someone
- netko može pratiti = someone can follow (we don’t say who)
itko = anyone (usually in negative or conditional sentences)
- može li itko pratiti? = can anyone follow?
- nitko ne može pratiti = no one can follow

So bilo tko stresses any person, without limitation, much like anybody in positive statements.

What does bilo gdje u svijetu mean, exactly? How is it different from svugdje or posvuda?

bilo gdje = anywhere (any place at all).
So bilo gdje u svijetu means:

anywhere in the world, from any place in the world

Other expressions:

svugdje / posvuda = everywhere (in all places)
- dostupno je svugdje = it is available everywhere
igdje = anywhere (mainly in negative / conditional contexts)
- nije dostupno igdje = it isn’t available anywhere

In the sentence, bilo tko može pratiti bilo gdje u svijetu emphasizes that:

any person, from any place in the world, can follow the lecture.

Why is the verb može singular in bilo tko može pratiti, not plural?

The grammatical subject here is bilo tko (anyone), which is singular:

tko (who / someone) behaves as a singular pronoun.
Therefore the verb must agree in number: bilo tko može.

Even though the meaning is any person, it doesn’t make the verb plural. Croatian verb agreement follows grammatical number, not the vague idea of “many possible people”.

Compare:

svatko može pratiti (everyone can follow) – still singular verb.
ljudi mogu pratiti (people can follow) – plural subject, plural verb.

What does pratiti mean in this context? Why not gledati?

The verb pratiti has several related meanings:

to follow (physically): pratiti nekoga = to follow someone
to follow (a process, news, a show, an event):
pratiti vijesti = to follow the news
pratiti prijenos = to follow a broadcast

In the sentence, pratiti predavanje means:

to follow (watch, listen to, keep up with) the lecture, usually live or as it’s happening.

You could say gledati predavanje (watch the lecture), but:

pratiti predavanje focuses more on attentively following the content, possibly in real time.
gledati is more literally to watch with your eyes, and can sound a bit more passive.

Both can be understood, but pratiti predavanje is very natural for an online event that people “follow” from wherever they are.

Is the word order fixed? Could I say znanstvenica na jednoj platformi drži online‑predavanje?

Croatian word order is fairly flexible, so several variants are possible and grammatical:

Na jednoj platformi znanstvenica drži online‑predavanje… (original)
Znanstvenica na jednoj platformi drži online‑predavanje…
Znanstvenica drži online‑predavanje na jednoj platformi…

Differences are mostly in emphasis:

Starting with Na jednoj platformi highlights the setting (on a platform) first.
Starting with Znanstvenica highlights the subject (the scientist).
Moving na jednoj platformi later often sounds more neutral or backgrounded.

All of these would be understood the same in most contexts; speakers use word order to subtly shift what feels like “given” vs “new” information.

Could the sentence use u svijetu alone, without bilo gdje?

If you said only:

…koje bilo tko može pratiti u svijetu,

it would be grammatical but a bit vague or odd in meaning – more like which anyone in the world can follow, without the clear sense of “from anywhere”.

The expression bilo gdje u svijetu is a fixed‑sounding formula meaning:

from any location in the world, there is no geographical restriction.

So bilo gdje u svijetu is the natural way to express “anywhere in the world”.