Learn Hardcore Croatian: Njihovo malo otkriće je da se voda drukčije ponaša na svjetlu nego u sjeni. - Their small discovery is that water behaves differently in the light than in the shadow.

Why is there no word for it in Njihovo malo otkriće je…? In English we say Their little discovery is that…, but Croatian has no visible subject pronoun.

In Croatian, you normally don’t use a separate pronoun it as a dummy subject like in English.

The subject of the sentence is the whole phrase Njihovo malo otkriće (their little discovery). Croatian doesn’t need an extra it because otkriće itself is the subject:

Njihovo malo otkriće je… = Their little discovery is…

So there is no equivalent of English dummy it here; the grammar is simply [subject] + je + [complement].

Why is it Njihovo malo otkriće, with njihovo and malo in that form?

Both njihovo and malo agree in gender, number and case with otkriće.

otkriće = discovery
- neuter gender
- singular
- nominative case (subject of the sentence)

So the modifiers must also be:

njihovo = their (possessive pronoun, neuter singular nominative)
malo = small/little (adjective, neuter singular nominative)

If the noun were feminine or masculine, those words would change:

Njihova mala tajna (fem.) – Their little secret
Njihov mali problem (masc.) – Their small problem

What exactly does malo otkriće mean here – “small” in size, or “not very important”?

In this context, malo otkriće most naturally means a minor / not very important discovery, rather than physically small.

Croatian malo with abstract nouns often suggests something like:

a small-scale or modest discovery,
not a big breakthrough, just a little finding.

It’s similar to saying a small discovery or a little discovery in English in the figurative sense of importance.

Why is it da se voda drukčije ponaša instead of something like an infinitive (“water to behave”)?

Croatian very often uses da + present tense to express what English might show with:

that + clause: that water behaves differently
for + noun + to + verb: for water to behave differently

Here:

da = that (a conjunction)
se voda ponaša = the water behaves

So da se voda drukčije ponaša literally is that the water behaves differently.

Using an infinitive after otkriće je would sound wrong here. The natural pattern is:

Njihovo otkriće je da… = Their discovery is that…

What is the purpose of se in da se voda drukčije ponaša? Why can’t we just say voda drukčije ponaša?

Ponašati se is a reflexive verb in Croatian. It’s always used with se:

ponašati se = to behave
ponašati (without se) would mean something else, or sound incomplete here.

So you must say:

voda se ponaša = the water behaves
and never
✗ voda ponaša

The se doesn’t really translate into a separate English word; it’s just part of the verb’s standard form.

Why is the word order da se voda ponaša, and not da voda se ponaša?

In Croatian, clitic words (short unstressed words like se, je, ga, mi, etc.) have preferred positions in the sentence. A common rule is that they come:

right after the first stressed word or phrase in the clause.

In da se voda ponaša:

da is the conjunction, and se naturally follows very early in the clause.
voda is stressed and comes after the clitic.

✗ da voda se ponaša sounds wrong because se is pushed too far away from the start of the clause. Native speakers instinctively put se where it is in the original sentence.

What does drukčije mean exactly? Is it the same as drugačije?

drukčije is an adverb meaning differently.

drukčije and drugačije are practically synonyms and both are common.
Many speakers will say drugačije more often in everyday speech.

In this sentence, you could also say:

…da se voda drugačije ponaša…

with no real change in meaning. It’s a stylistic / regional preference.

Why is drukčije placed before ponaša and not somewhere else, like voda se ponaša drukčije?

Both positions are possible:

voda se drukčije ponaša
voda se ponaša drukčije

Both mean the water behaves differently.

In Croatian, adverbs like drukčije are fairly flexible in position, especially around the main verb. The chosen order here (drukčije ponaša) is perfectly natural and doesn’t change the meaning; it might slightly emphasize the manner (differently) but that’s subtle.

Why is it na svjetlu but u sjeni? In English we’d just say “in the light” and “in the shade”.

This is largely about typical collocations and preposition choice in Croatian:

na svjetlu = in the light
- literally on light, but idiomatically in the light
u sjeni = in the shade

The difference:

na
- locative often suggests being on / in the presence of an open surface or exposure:
  - na suncu – in the sun
  - na svjetlu – in (the) light
u
- locative suggests being inside / within something:
  - u sjeni – in the shade
  - u mraku – in the dark

So you just have to learn these as natural combinations: na svjetlu, na suncu, but u sjeni, u mraku.

What case are svjetlu and sjeni in, and why do they change from svjetlo and sjena?

Both svjetlu and sjeni are in the locative case, because they follow prepositions na and u with the meaning in/on (a place or situation).

Base forms:

svjetlo (neuter nominative singular) → svjetlu (locative singular)
sjena (feminine nominative singular) → sjeni (locative singular)

With these prepositions:

na + locative: na svjetlu – in the light
u + locative: u sjeni – in the shade

So the change in endings (-o → -u, -a → -i) is regular case inflection.

What does nego do here? How is it different from od in comparisons?

Nego is used after a comparative when you’re contrasting one thing with another, especially when something is different/better/worse than something else.

Here:

drukčije … nego u sjeni = differently … than in the shade

General pattern:

bolji nego ti – better than you
drugačiji nego prije – different than before

Od is also used with comparatives, especially with adjectives and adverbs:

veći od njega – bigger than him
brži od auta – faster than a car

In this sentence, drukčije nego u sjeni is the natural choice; drukčije od u sjeni would be ungrammatical.

Could we rephrase the sentence as Voda se ponaša drukčije na svjetlu nego u sjeni? Would that change the meaning?

You can absolutely say:

Voda se ponaša drukčije na svjetlu nego u sjeni.

That’s a perfectly natural standalone sentence meaning:

Water behaves differently in the light than in the shade.

The original sentence:

Njihovo malo otkriće je da se voda drukčije ponaša na svjetlu nego u sjeni.

simply wraps that idea inside Njihovo malo otkriće je da… (Their little discovery is that…). The core proposition voda se (drukčije) ponaša na svjetlu nego u sjeni stays the same.

Why aren’t there any articles like the or a before voda, svjetlu, and sjeni?

Croatian does not have articles (a/an, the) the way English does. Nouns normally appear without any article:

voda – water / the water
svjetlo / svjetlu – light / the light
sjena / sjeni – shade / the shade

Context tells you whether English would need a, the, or no article:

voda here is understood like water or the water in general.
na svjetlu is understood as in the light.
u sjeni is understood as in the shade.

So you don’t need to add anything like the in Croatian; the bare noun is enough.