Siskoni pelaa tennistä koulun kentällä torstai-iltaisin.

My sister plays tennis on the school field on Thursday evenings.

Breakdown of Siskoni pelaa tennistä koulun kentällä torstai-iltaisin.

• minun: my
• sisko: the sister
• -llä: on
• koulu: the school
• pelata: to play
• kenttä: the field
• tennis: the tennis
• torstai-iltaisin: on Thursday evenings

Questions & Answers about Siskoni pelaa tennistä koulun kentällä torstai-iltaisin.

Why does the sentence use siskoni instead of minun sisko?

Siskoni already means my sister in one word.

• sisko = sister
• -ni = my (1st person possessive suffix)

So siskoni = my sister.

In standard Finnish, you cannot normally say minun sisko without the possessive ending; it should be:

• siskoni
• or minun siskoni (more emphatic: my sister, as opposed to someone else’s)

Using only siskoni is the most neutral, normal way to say my sister here.

Can I also say Minun siskoni pelaa tennistä…? Does it sound different?

Yes, Minun siskoni pelaa tennistä… is correct.

Nuance:

• Siskoni pelaa tennistä… – neutral, simple statement: My sister plays tennis…
• Minun siskoni pelaa tennistä… – adds emphasis or contrast: My sister plays tennis (maybe someone else’s doesn’t, or you’re stressing that it’s specifically yours).

Grammatically both are fine; the version without minun is more typical in neutral written Finnish.

Why is there no separate word for “my”? Where did it go?

Finnish often attaches possession directly to the noun with a suffix instead of using a separate word.

Pronouns + suffixes:

• -ni = my
• -si = your (singular)
• -mme = our
• -nne = your (plural)

Examples:

• kirja = a book → kirjani = my book
• auto = a car → autosi = your car
• sisko = sister → siskoni = my sister

The separate pronoun (minun, sinun, etc.) is optional and mainly used for emphasis or clarity, not required every time like in English.

Why is pelaa used here – does it mean “plays” or “is playing”?

Finnish has only one present tense form; pelaa can mean:

• plays (habitual):

  • Siskoni pelaa tennistä torstai-iltaisin.
    My sister plays tennis on Thursday evenings. (regular habit)

• is playing (right now), if you add a time word like nyt:

  • Siskoni pelaa nyt tennistä.
    My sister is playing tennis now.

So pelaa covers both English plays and is playing. Context (here: torstai-iltaisin) tells us it’s a regular habit.

Why is tennistä in this form, not just tennis?

Tennistä is the partitive singular of tennis.

With many sports, Finnish uses the partitive after pelata (to play), especially when talking about the activity in general:

• pelata jalkapalloa – to play football/soccer
• pelata koripalloa – to play basketball
• pelata tennistä – to play tennis

Reasons:

1. The action is seen as ongoing / not a single completed object. You’re doing “some tennis” as an activity, not “one whole tennis”.
2. The amount is not countable: you don’t “finish” a specific tennis in the same way you might “eat an apple”.

Using tennis in the basic form here (pelaa tennis) would be ungrammatical.

Could I ever say pelaa tenniksen?

In normal language, no.

• Pelaa tennistä is the standard and natural way: plays tennis.
• Pelaa tenniksen is wrong or at best extremely strange; it would sound like you’re treating tennis as one specific, bounded object to be completed, which doesn’t fit how the sport is conceptualized.

So: stick with pelata tennistä.

Why is koulun used – what does that ending mean?

Koulun is the genitive singular of koulu (school).

• koulu = school
• koulun = school’s / of the school

In koulun kentällä, the genitive shows a relationship similar to English ’s or of:

• koulun kenttä – the school’s field/court
• koulun kentällä – on the school’s field/court

So koulun tells us which field it is: the one belonging to (or associated with) the school.

What does kentällä mean, and why that particular ending?

Kentällä is kenttä (field/court) in the adessive case.

• kenttä = field, court
• kentällä = on/at the field/court

The adessive ending -lla / -llä often corresponds to English on / at for surfaces and open areas:

• pöydällä – on the table
• torilla – at/on the market square
• kentällä – on/at the field or court

If you used kentässä (in the field), that would literally mean inside the field (nonsensical here). So kentällä (on/at the field) is the correct spatial case.

Why is there no separate word for “at” or “on” in “at the school court” and “on Thursday evenings”?

Instead of prepositions like at, on, in, Finnish normally uses case endings on nouns/adverbs:

• koulun kenttä → koulun kentällä

  • -llä encodes “on / at”: on the school court

• torstai-ilta (Thursday evening) → torstai-iltaisin

  • -isin here encodes “on (Thursday evenings), regularly”

So koulun kentällä already means at the school’s field without a separate word like at, and torstai-iltaisin means on Thursday evenings without a separate on.

What exactly does torstai-iltaisin mean, and how is it built?

Torstai-iltaisin means on Thursday evenings (habitually / regularly).

Structure:

• torstai = Thursday
• ilta = evening
• combined: torstai-ilta = Thursday evening
• • -isin (distributive ending) → torstai-iltaisin

The ending -isin is used with time expressions to mean “on Xs / at X times (repeatedly, as a habit)”:

• maanantaisin – on Mondays
• sunnuntaisin – on Sundays
• aamuisin – in the mornings (regularly)
• öisin – at night(s), during the nights (regularly)
• torstai-iltaisin – on Thursday evenings (regularly)

So torstai-iltaisin tells us this happens habitually, not just once.

What’s the difference between torstai-iltaisin, torstaisin, and torstai-iltana?

They’re all related but have different nuances:

1. torstai-iltaisin

   • on Thursday evenings (regularly)
   • Emphasizes both the day and the time of day, and that it’s a habit.

2. torstaisin

   • on Thursdays (regularly)
   • Says it happens on Thursdays, but doesn’t specify morning/afternoon/evening.

3. torstai-iltana

   • on Thursday evening (one specific occasion)
   • The -na ending (essive) is typically used for a single point in time:
     
     • Torstai-iltana siskoni pelaa tennistä.
       My sister will play tennis on Thursday evening (this coming Thursday, for example).

So:

• repeated habit, Thursday evenings → torstai-iltaisin
• repeated habit, every Thursday (any time) → torstaisin
• one specific Thursday evening → torstai-iltana

Why is there a hyphen in torstai-iltaisin?

The hyphen links the two parts of the compound time expression:

• torstai (Thursday)
• ilta (evening)
• • -isin on the whole thing → torstai-iltaisin

You often see a hyphen in Finnish when:

• two nouns form a compound, and
• a case ending (here -isin) is attached to the whole phrase.

Similar patterns:

• maanantai-aamuisin – on Monday mornings
• lauantai-iltaisin – on Saturday evenings

The hyphen makes it clear that torstai and ilta belong together as one time expression.

Can the word order change, for example: Torstai-iltaisin siskoni pelaa tennistä koulun kentällä?

Yes. Finnish word order is quite flexible. All of these are grammatical:

• Siskoni pelaa tennistä koulun kentällä torstai-iltaisin.
• Torstai-iltaisin siskoni pelaa tennistä koulun kentällä.
• Koulun kentällä siskoni pelaa tennistä torstai-iltaisin.

Changes in word order mostly affect emphasis and what is presented as known vs. new information:

• Starting with Torstai-iltaisin… emphasizes the time: As for Thursday evenings, my sister plays tennis…
• Starting with Siskoni… emphasizes who we’re talking about first.

The basic meaning remains the same.

Why doesn’t the sentence just say Hän pelaa tennistä… for “She plays tennis…”?

It could say that, but it wouldn’t mean exactly the same thing.

• Hän pelaa tennistä koulun kentällä torstai-iltaisin.
  = He/She plays tennis at the school court on Thursday evenings.

This tells you about some person already known from context, but it does not say that person is your sister.

• Siskoni pelaa tennistä… specifically says my sister.
  The possessive suffix -ni is carrying the meaning my.

So if you want to communicate that the person is your sister, siskoni is the right choice.