Learn Hardcore Finnish: Siskoni pelaa koripalloa pienessä hallissa, jossa katto on matala. - My sister plays basketball in a small hall where the ceiling is low.

The verb pelata (to play, as in games and sports) almost always takes its object in the partitive case when you’re talking about playing a sport or a game in general.

koripallo = basketball (nominative)
koripalloa = basketball (partitive singular)

So pelaa koripalloa is the usual, idiomatic way to say “plays basketball”.

More technically:

pelata + partitive is used for:
- activities that are not seen as having a clear, completed end (ongoing/indefinite)
- and especially for sports and games: pelata jalkapalloa, pelata tennistä, pelata shakkia

Using koripallo (nominative) here would sound wrong to a native speaker in this meaning.

What does pienessä hallissa literally mean, and why do both words change?

Pienessä hallissa means “in a small hall”.

Base forms:

pieni = small
halli = hall

Finnish marks “in” using the inessive case, with the ending -ssa / -ssä.

Both the adjective and the noun take the same case and number, so they “agree”:

pieni halli (nominative singular) → “a small hall”
pienessä hallissa (inessive singular) → “in a small hall”

Breakdown:

piene-ssä:
- stem: piene- (grade change from pieni)
- ending: -ssä = in
halli-ssa:
- stem: halli-
- ending: -ssa = in

So: pienessä hallissa = “in (a) small hall”.

Why is the ending -ssä in pienessä but -ssa in hallissa?

This is due to vowel harmony.

Finnish has two main sets of vowels:

Front vowels: ä, ö, y
Back vowels: a, o, u
Neutral: e, i (these go with either front or back vowels)

The case ending adapts to the word:

If the word has front vowels, you use the front-vowel version of the ending: -ssä
If the word has back vowels, you use the back-vowel version: -ssa

Check the vowels:

pieni → vowels: i, e, i (neutral only) → neutral words follow front-vowel endings → pienessä
halli → vowels: a, i, i (contains a, a back vowel) → use -ssa → hallissa

So you get pienessä hallissa: front form on the adjective, back form on the noun, because each one follows its own vowel harmony rules.

What is the function of jossa and why not missä?

Both are related to the idea of “where / in which”, but they are used differently.

missä = where? (question word)
jossa = in which / where (relative pronoun)

In this sentence:

jossa katto on matala = “where the roof is low” or “in which the roof is low”

Here jossa refers back to pienessä hallissa:

pienessä hallissa, jossa katto on matala
→ “in a small hall, in which the roof is low”

You wouldn’t use missä here, because this is not a direct question; it is a relative clause describing the hall. Relative clauses use joka and its case forms (jossa, josta, johon, etc.), not the question words.

Why is there a comma before jossa?

The comma marks the start of a relative clause that adds extra information about the hall.

Main clause: Siskoni pelaa koripalloa pienessä hallissa
Relative clause: jossa katto on matala

In standard written Finnish, a comma is normally placed before a joka/jossa/johon… clause when it adds descriptive information (like an English “which…” clause).

So the comma before jossa is the usual punctuation rule, similar to English:

“My sister plays basketball in a small hall, where the ceiling is low.”

Why is it katto on matala and not katto on matalaa or matalana?

Here matala is a predicative adjective describing a state:

katto = the roof (subject)
on = is
matala = low (predicative adjective)

With a permanent or generic characteristic, Finnish typically uses the nominative form for the adjective:

Hän on pitkä. – He/She is tall.
Vesi on kylmää. vs Vesi on kylmä. (subtle nuance, see below)
Katto on matala. – The roof is low.

Some nuances:

katto on matala
- neutral statement about a permanent characteristic: “the roof is (a) low (one)”.
katto on matalaa (partitive)
- would sound odd here; partitive predicative is more typical with substances or when emphasizing some amount or temporariness (e.g. “The water is cold-ish / sort of cold” type nuances).
matalana (essive)
- would imply “as low / in the role of being low”, used in special structures (e.g. “Hän oli opettajana” = “He was working as a teacher”).
- Not appropriate for a simple “the roof is low” description.

So katto on matala is the normal, straightforward way to describe the roof’s height.

Does pelaa already show who is doing the action? Why is there no hän?

Yes, pelaa is the 3rd person singular form of pelata:

minä pelaan – I play
sinä pelaat – you (sg) play
hän pelaa – he/she plays

In the sentence, the subject is siskoni (my sister). Finnish usually doesn’t add an extra pronoun (hän) when the subject is already there:

Siskoni pelaa koripalloa… – natural
Siskoni hän pelaa koripalloa… – normally wrong / overly emphatic

So:

siskoni = subject
pelaa = verb already in 3rd person singular
There is no need to add hän.

Could you change the word order, like Siskoni pelaa pienessä hallissa koripalloa? Would that change the meaning?

Yes, you can change the word order, and Finnish allows quite a lot of flexibility. The meaning in terms of basic facts stays the same, but the emphasis can shift.

Original:

Siskoni pelaa koripalloa pienessä hallissa, jossa katto on matala.
- Normal, neutral emphasis: what she plays (basketball) is mentioned right after the verb.

Variant:

Siskoni pelaa pienessä hallissa koripalloa, jossa katto on matala.
- This is possible, but now pienessä hallissa is immediately after the verb, which slightly foregrounds the location before mentioning what she plays.
- Also, with the relative clause right after koripalloa, it can sound a bit clumsier; written Finnish usually keeps pienessä hallissa next to jossa so it’s clear what jossa refers to.

A more natural alternative if you want to highlight the place might be:

Siskoni pelaa pienessä hallissa koripalloa. (no relative clause)

But with the relative clause, the original word order is the smoothest:

…koripalloa pienessä hallissa, jossa katto on matala.

Is there any difference between halli and words like sali or urheiluhalli here?

Yes, they’re related but not identical in meaning.

halli
- a hall in general: can be a sports hall, an exhibition hall, a big indoor space.
- In context, it will usually be understood as a sports hall if you talk about playing basketball.
urheiluhalli
- explicitly means sports hall (urheilu = sport).
- More specific: you know it’s a place for sports.
sali
- a hall/room, often used for larger rooms inside a building:
  - liikuntasali = gym (school gym)
  - tanssisali = dance hall
- salissa can mean “in the hall / in the big room”.

In your sentence, halli is perfectly fine and natural. If you wanted to be more specific, you could say:

pienessä urheiluhallissa – in a small sports hall
pienessä liikuntasalissa – in a small gym (especially in a school setting)

But grammatically they all follow the same patterns you see in pienessä hallissa.