Pokraj škole je mali vrtuljak, ali djeca danas radije trče.

Because pokraj requires the genitive case.

• škola = nominative singular, the basic dictionary form
• škole = genitive singular

So:

• pokraj škole = beside / near the school

This is very common in Croatian: many prepositions force a specific case, and pokraj takes the genitive.

Pokraj means beside, next to, or near.

In this sentence, Pokraj škole gives the location: the carousel is beside the school.

It is similar to pored or sometimes kraj, though exact usage can vary by region and style. For a learner, you can usually understand pokraj škole as beside the school.

This is because je is a clitic in Croatian. Clitics usually go in the second position in the clause.

So Croatian naturally says:

• Pokraj škole je mali vrtuljak.

Literally, the first unit is Pokraj škole, and then the clitic je comes after it.

You could also say:

• Mali vrtuljak je pokraj škole.

That is also correct, but it puts the focus a little differently. The original sentence starts with the location, which sounds very natural.

Mali vrtuljak is in the nominative singular masculine.

Why?

Because it is the thing being identified in the sentence:

• Pokraj škole je mali vrtuljak.
• There is a small carousel beside the school.

The noun vrtuljak is masculine singular, so the adjective must match it:

• mali = masculine singular nominative
• vrtuljak = masculine singular nominative

Croatian adjectives agree with nouns in gender, number, and case.

Here vrtuljak means a small carousel / merry-go-round, especially the kind children play on.

It comes from the idea of turning or spinning. In different contexts, similar words can refer to other rotating things, but in this sentence it clearly means a children’s ride or playground spinner.

Djeca means children, so it is treated as plural in meaning and takes a plural verb:

• djeca trče = the children run / are running

This is an irregular word, because the singular is:

• dijete = child

and the plural is:

• djeca = children

So even though the form may not look familiar at first, you should learn dijete → djeca as an irregular pair.

Radije means rather or preferably.

In this sentence:

• djeca danas radije trče
• the children would rather run today
• or more naturally: today the children prefer running

It expresses preference.

A very useful pattern is:

• radije ... nego ... = rather ... than ...

For example:

• Djeca radije trče nego sjede.
• The children would rather run than sit.

Croatian often expresses preference with radije + finite verb.

So instead of copying the English structure prefer to run, Croatian naturally says:

• radije trče = would rather run / prefer running

This is a normal Croatian way to express what someone prefers doing.

A related word is:

• rado = gladly, willingly
• radije = rather, more willingly

So radije is basically the comparative form.

Danas means today.

It tells you when the children prefer running. In Croatian, adverbs like this can move around fairly freely depending on emphasis:

• Djeca danas radije trče.
• Danas djeca radije trče.
• Djeca radije trče danas.

All are possible, though the first is the most neutral here.

Because Croatian does not have articles like English a / an / the.

So:

• škole can mean school / the school
• mali vrtuljak can mean a small carousel or the small carousel
• djeca can mean children / the children

The exact meaning is understood from context.

That is why English translations often add the even though there is no separate Croatian word for it.

Yes. Croatian word order is much more flexible than English word order.

For example, these are all possible:

• Pokraj škole je mali vrtuljak, ali djeca danas radije trče.
• Mali vrtuljak je pokraj škole, ali djeca danas radije trče.
• Ali djeca danas radije trče could also be rearranged slightly for emphasis.

The original version starts with Pokraj škole, which puts the location first, almost like setting the scene.

So the grammar is not only about what words are used, but also about what the speaker wants to emphasize.

Ali means but.

It connects the two ideas:

• there is a small carousel beside the school
• but the children would rather run today

So it introduces a contrast. The contrast is that even though there is something fun to play on, the children prefer a different activity today.