Learn Hardcore Finnish: Lapset leikkivät puun ympärillä puistossa. - The children play around the tree in the park.

Finnish has no articles like the or a/an at all.
Definiteness is understood from context, word order, and sometimes other words, not from a specific article.

So Lapset leikkivät puun ympärillä puistossa can mean:

The children are playing around the tree in the park.
Children are playing around a tree in a park.

Which one is correct depends on what has been mentioned before and what both speakers know. If the speaker and listener both know which children, which tree, and which park, the English translation will naturally use the.

How does leikkivät correspond to English are playing / play?

Finnish has only one present tense; it covers both English present simple and present continuous.

He leikkivät can translate as:
- They play, or
- They are playing

Context decides which English form you choose.

If you really want to emphasize the ongoing activity (similar to English are playing right now), Finnish often uses a construction with olla (to be) + a special form of the main verb, for example:

Lapset ovat leikkimässä puistossa.
= The children are (currently) playing in the park.

But Lapset leikkivät puun ympärillä puistossa is perfectly fine for normal “are playing” in most contexts.

Why does leikkivät end in -vät, not -vat?

The ending -vat / -vät marks 3rd person plural (they).

Which one you use depends on vowel harmony:

After back vowels (a, o, u) → -vat
After front vowels (ä, ö, y) and also e, i → -vät

The stem of leikkiä (to play) in the present is leiki- / leikk(i)-, which contains the front vowel i.

So:

he leikkivät = they play / are playing

Compare:

he laulavat (they sing) → laula- has a, a back vowel → -vat
he syövät (they eat) → syö- has ö, a front vowel → -vät

Why is it puun and not puu for tree?

Puun is the genitive singular of puu (tree).

Many Finnish postpositions (words like in front of, around, behind) require their complement noun to be in the genitive case. Ympärillä (around) is such a postposition.

So:

puu = a/the tree (basic form)
puun ympärillä = around the tree
(literally: tree’s around)

Pattern:

talo → talon edessä = in front of the house
pöytä → pöydän alla = under the table
puu → puun ympärillä = around the tree

The structure is: [genitive noun] + [postposition].

Why does ympärillä come after puun, unlike English “around the tree”?

Finnish uses both prepositions (before the noun) and postpositions (after the noun).
Ympärillä is a postposition, so it comes after its noun:

puun ympärillä = around the tree

The noun it refers to (puu) must be in the genitive: puun.

Compare:

ennen iltaa = before the evening (ennen = preposition, comes first)
talon takana = behind the house (takana = postposition, comes after)

So the word order puun ympärillä is normal Finnish grammar, not a stylistic choice.

What’s the role of the ending -llä in ympärillä?

The -llä part in ympärillä is historically the adessive case ending (related to on / at / by something).

ympäri = around
ympärillä ≈ “at around / in the area around”

As a learner, you mainly just need to remember the fixed form ympärillä and that it usually takes a genitive noun before it:

puun ympärillä = around the tree
talon ympärillä = around the house
kaupungin ympärillä = around the city

You don’t normally change ympärillä itself; you change the noun that precedes it.

Why is it puistossa and not just puisto?

Puistossa is the inessive case of puisto (park), and it means in the park.

Finnish often uses case endings instead of prepositions like in, on, at.

puisto = park (basic form)
puistossa = in the park (inessive, -ssa / -ssä)

Some related forms:

puistoon (illative) = into the park
puistosta (elative) = out of / from the park

So Lapset leikkivät puistossa literally is The children play in-the-park.

Is puistossa “in a park” or “in the park”? How do I show that in Finnish?

Puistossa by itself does not show whether it is a park or the park. Finnish case endings express location, not definiteness.

So puistossa can mean:

in a park
in the park

Again, context determines which English article is appropriate. For example:

If you’ve already been talking about a specific park:
Eilen menimme puistoon. Tänään lapset leikkivät puistossa.
→ Yesterday we went to the park. Today the children are playing in the park.

If you truly need to stress “a certain specific park” or “some park or other”, you have to add other words (like demonstratives, adjectives), but normally Finnish just doesn’t mark this grammatically.

Can the word order be changed, for example Puistossa lapset leikkivät puun ympärillä?

Yes. Finnish word order is fairly flexible, because roles are marked with case endings rather than position.

All of these are grammatically correct:

Lapset leikkivät puun ympärillä puistossa.
Lapset leikkivät puistossa puun ympärillä.
Puistossa lapset leikkivät puun ympärillä.
Puun ympärillä lapset leikkivät puistossa.

The basic neutral order for a simple sentence is often:

Subject – Verb – Other elements
→ Lapset leikkivät puun ympärillä puistossa.

Moving parts around typically changes emphasis / focus, not the core meaning. For example, starting with Puistossa highlights the place first.

How would the sentence change if there was only one child instead of several?

You’d put the subject and the verb in the singular:

Lapsi leikkii puun ympärillä puistossa.
- lapsi = child (singular)
- leikkii = (he/she) plays, is playing (3rd person singular)

The rest stays the same:

puun (tree’s, genitive)
ympärillä (around)
puistossa (in the park)

So:

Lapset leikkivät puun ympärillä puistossa. = The children are playing…
Lapsi leikkii puun ympärillä puistossa. = The child is playing…

Could you leave out one of the location expressions, like just say Lapset leikkivät puistossa?

Yes. Both location parts are optional, depending on how much detail you want:

Lapset leikkivät.
= The children are playing. (No location at all)
Lapset leikkivät puistossa.
= The children are playing in the park. (Place, but not where exactly in the park)
Lapset leikkivät puun ympärillä.
= The children are playing around the tree. (We know they’re around a tree, but not necessarily that it’s in a park)
Lapset leikkivät puun ympärillä puistossa.
= The children are playing around the tree in the park. (more specific)

Finnish simply stacks these phrases, and each added element makes the picture more detailed.