Learn Hardcore Croatian: Jednom sam zaboravio novčanik kod kuće i pitao se što da radim u supermarketu. - Once I forgot my wallet at home and wondered what to do in the supermarket. male speaker

Jednom means once / one time in this context (not one as in one apple). It’s an adverb of time, like once or one day in English.

You could move it around a bit without changing the meaning much:

Jednom sam zaboravio novčanik kod kuće… (neutral, very natural)
Jednom, kad sam bio u supermarketu, zaboravio sam novčanik kod kuće.
Novčanik sam jednom zaboravio kod kuće… (more emphasis on novčanik)

It usually appears near the beginning of the sentence or near the verb it modifies, but Jednom sam zaboravio… is the most typical neutral order here.

Why is it Jednom sam zaboravio and not Jednom zaboravio sam?

Because of Croatian clitic rules. The word sam (I am / I have) is a clitic and normally wants to be in second position in the clause.

Sentence starts with:

Jednom – first stressed word
sam – goes into second position
zaboravio – main verb

So Jednom sam zaboravio… is correct.

Jednom zaboravio sam… sounds wrong and unnatural to native speakers, because sam is pushed too far to the right instead of staying in that second position.

Why is the past tense split as sam zaboravio instead of one word?

Croatian forms the (simple) past tense with two parts:

an auxiliary verb (sam, si, je, smo, ste, su)
a past participle (zaboravio, zaboravila, zaboravili…)

So:

(Ja) sam zaboravio = I forgot
(Ti) si zaboravio = You forgot (to a male)
(Ona) je zaboravila = She forgot

They are always two separate words. The auxiliary (sam) behaves like a clitic and goes near the beginning of the clause (usually second position), while the participle (zaboravio) can move a bit more freely.

Why is novčanik in this form? Shouldn’t it change for the object case?

Novčanik is a masculine inanimate noun. In Croatian, for masculine inanimate nouns, the nominative and accusative singular forms are the same:

Nominative (subject):
- Novčanik je na stolu. – The wallet is on the table.
Accusative (direct object):
- Vidim novčanik. – I see the wallet.
- Zaboravio sam novčanik. – I forgot the wallet.

So even though novčanik is an object here (accusative case), it looks exactly like the basic dictionary form.

What is the difference between kod kuće and u kući?

Both involve kuća (house), but they are used differently:

kod kuće = at home (location in the sense of “my/our home”)
- Zaboravio sam novčanik kod kuće. – I forgot my wallet at home.
u kući = in the house (inside a building, more literal)
- Psi su u kući. – The dogs are in the house.

In this sentence, kod kuće is correct because the idea is “I left it at home”, not just physically inside some house.

Why is it pitao se and not pitao sam se? Isn’t sam needed?

The fully explicit form would be:

Jednom sam zaboravio novčanik kod kuće i pitao sam se što da radim u supermarketu.

But in Croatian, when two clauses share the same subject and tense, the auxiliary sam is often dropped in the second part to avoid repetition. Native speakers do this a lot in spoken and informal written language.

So:

…sam zaboravio… i pitao se…

is understood as:

…sam zaboravio… i (sam) se pitao…

The se (reflexive pronoun) stays, because it’s part of pitati se = to wonder / to ask oneself. The dropped sam is just “I (have)” in the past tense and is recoverable from context.

Why is se after pitao and not se pitao or pitao sam se? How does the reflexive se work here?

The verb pitati se is reflexive: to ask oneself / to wonder.

Pitao sam se… – I wondered / I was asking myself…

In the shorter version without sam, you get:

pitao se – se is a clitic and needs to come early in the phrase, usually right after the first stressed word in its clause. Here the first stressed word is pitao, so:
pitao se is correct and natural.
se pitao is ungrammatical in neutral word order.

You could say:

Jednom sam se pitao što da radim…

Here sam (clitic) goes in second position in the clause, and se comes right after it: sam se pitao. The given sentence just omits sam in the second part.

What does što da radim literally mean, and why is it present tense radim if the situation is in the past?

Što da radim? is a very common pattern:

što = what
da
- present tense (radim) = something like an English “should / is to / am supposed to do” here

So što da radim? is best translated as:

What should I do? / What am I supposed to do?

This da + present construction is often used for wishes, commands, recommendations, and “what to do” situations, and its time reference comes from context, not from the present tense form itself.

In your sentence, it’s inside the past-time frame:

…i pitao se što da radim u supermarketu.
= …and I wondered what I should do in the supermarket.

Even though radim is a present-form verb, the whole thought (the “wondering”) is located in the past.

Could I say što ću raditi instead of što da radim?

You could, but the nuance changes:

što da radim – what should I do / what am I to do (focus on choosing an action, a decision)
što ću raditi – what I will be doing (more neutral future prediction, less about choice)

In this context (standing in a supermarket without your wallet, unsure what to do), što da radim is the natural, idiomatic choice because it expresses uncertainty and seeking a solution.

Why is it u supermarketu and not u supermarket? What case is that?

After the preposition u, you get:

Accusative for motion into something:
- Idem u supermarket. – I’m going into the supermarket.
Locative for location in/at something:
- Sam u supermarketu. – I am in the supermarket.

In your sentence:

…što da radim u supermarketu.

There is no movement; you are already inside / at the supermarket. So supermarketu is in the locative case (singular masculine), which for many masculine nouns ends in -u after u when it means “in/at (a place)”.

Could I change the word order to Jednom sam kod kuće zaboravio novčanik? Does it sound odd?

You can say:

Jednom sam kod kuće zaboravio novčanik…

This is grammatically correct and understandable. The nuance is slightly different:

Jednom sam zaboravio novčanik kod kuće…
– neutral; the new information is that you forgot the wallet, and that it was at home.
Jednom sam kod kuće zaboravio novčanik…
– a bit more focus on the location (“once, at home, I forgot my wallet”), as if contrasting it with forgetting it somewhere else on other occasions.

Both are fine; the original is the most neutral way to say it.

What’s the difference between što and šta? Could I say šta da radim here?

Što is the standard Croatian form for what.

Šta is very common in colloquial speech and in some regional varieties (especially influenced by Serbian/Bosnian/Montenegrin).

In everyday conversation in much of Croatia, you will absolutely hear:

Šta da radim?

In more formal or standard Croatian (e.g., in writing, on exams), što da radim is preferred. In your sentence, both are understood; što is just the standard choice.