Moj unuk danas prvi put ide u školu, dok unuka još ide u vrtić.

Moj means my, and it has to agree with the noun it describes.

• unuk = grandson
• unuk is masculine singular nominative
• so the correct possessive form is moj

Compare:

• moj unuk = my grandson
• moja unuka = my granddaughter

So moj is used because unuk is masculine.

They are two related family words:

• unuk = grandson
• unuka = granddaughter

So in this sentence:

• Moj unuk = My grandson
• dok unuka još ide u vrtić = while my granddaughter still goes to kindergarten

A learner should also know that unuka can sometimes be a different grammatical form of unuk in other contexts, but here it clearly means granddaughter, because it is the subject of the second clause.

Because Croatian often leaves out words that are already obvious from context.

So:

• Moj unuk danas prvi put ide u školu, dok unuka još ide u vrtić.

naturally means:

• My grandson is going to school for the first time today, while my granddaughter is still going to kindergarten.

You could say dok moja unuka još ide u vrtić, but it is not necessary. Leaving it out sounds natural because the listener already understands whose granddaughter is meant.

It means today for the first time.

Breakdown:

• danas = today
• prvi put = the first time / for the first time

Together, danas prvi put ide u školu means that today is the first day he is going to school.

Prvi put is a very common expression in Croatian.

Examples:

• Vidim ga prvi put. = I’m seeing him for the first time.
• Prvi put sam u Zagrebu. = I’m in Zagreb for the first time.

Because after u, Croatian uses different cases depending on meaning.

With movement toward a place, u takes the accusative.

Here:

• škola = nominative
• školu = accusative

Since ide means goes/is going, the sentence expresses movement toward school:

• ide u školu = goes to school

Compare:

• Ide u školu. = He is going to school.
• On je u školi. = He is at school / in school.

So:

• u školu = direction, destination
• u školi = location

Because different nouns decline differently.

• škola is a feminine noun, so its accusative singular changes:
  • škola → školu
• vrtić is a masculine inanimate noun, and for many masculine inanimate nouns, the accusative singular is the same as the nominative:
  • vrtić → vrtić

So:

• u školu
• u vrtić

Both are accusative after u with movement, but the forms happen to look different because the nouns belong to different declension patterns.

Here dok means while or whereas.

It connects two ideas:

• the grandson is going to school for the first time
• the granddaughter still goes to kindergarten

So it creates a contrast between the two.

In this sentence, dok is close to:

• while
• whereas

So the sense is:

• My grandson is going to school for the first time today, while/whereas my granddaughter still goes to kindergarten.

Because dok introduces a second clause.

The sentence has two parts:

1. Moj unuk danas prvi put ide u školu
2. dok unuka još ide u vrtić

Croatian usually separates such clauses with a comma, especially when a conjunction like dok introduces contrast or a subordinate clause.

So the comma is normal and expected here.

Here još means still.

So:

• unuka još ide u vrtić = the granddaughter still goes to kindergarten

The idea is that she has not started school yet.

Još is a very common word and can mean different things in different contexts, such as:

• still
• yet
• more / another

But in this sentence, still is the best translation.

Because Croatian often uses the present tense for something happening now, today, or in a very immediate real-world situation.

So danas ... ide u školu can naturally mean:

• he is going to school today
• he starts school today, depending on context

This is very normal. Croatian does not need a special form here.

Also, ide u školu can be understood both literally and institutionally:

• literally: he is going to the school building
• more naturally here: he is starting / attending school

Context gives the intended meaning.

Because Croatian has no articles.

So Croatian simply says:

• unuk = grandson / the grandson / a grandson
• škola = school / the school
• vrtić = kindergarten / the kindergarten

English needs articles, but Croatian usually does not. The exact meaning is understood from context.

That is why:

• ide u školu = goes to school not something like goes to the school with a separate word for the

It usually means more than simple physical movement. In sentences like this, ići u školu often means to attend school or to start school as an institution.

So:

• Moj unuk danas prvi put ide u školu is not just about walking into a building
• it means today is his first time going as a school pupil

Likewise:

• ići u vrtić = to go to kindergarten / attend kindergarten

These are very common expressions in Croatian.