Learn Hardcore Finnish: Minä juon kahvia opiskellessani suomea.

In this sentence, kahvia is used because you are drinking an unspecified amount of coffee, not a specific, countable unit like “one coffee”. In Finnish, the partitive is typical for:

Uncountable “mass” nouns:
- juon vettä – I drink water
- syön riisiä – I eat rice
Indefinite amounts:
- juon kahvia – I (drink some) coffee

If you used kahvin (accusative/genitive), it would sound more like a whole, known unit of coffee, e.g. a cup you have in mind.

So:

Juon kahvia. – I drink coffee / I’m drinking coffee (general, some amount).

What exactly does opiskellessani mean and how is it formed?

Opiskellessani literally means “while I am studying” or “when I study”, with the subject I included inside the word.

It’s built like this:

opiskella – to study
opiskelle- – stem used for infinitive/participle forms
opiskellessa – the 3rd infinitive in the inessive case = “while studying”
opiskellessa + ni – adding -ni (my) as a possessive suffix to show the subject is I

So opiskellessani = opiskellessa + ni =
→ “while my studying (is happening)”
→ more naturally: “while I’m studying”

Why does the “I” appear twice: Minä and -ni in opiskellessani? Is that necessary?

The two I-markers have different jobs:

Minä is the subject of the main clause: Minä juon kahvia – I drink coffee.
-ni in opiskellessani marks the subject of the subordinate action “studying”.

You can:

Keep both:
- Minä juon kahvia opiskellessani suomea.
Drop Minä (but keep -ni):
- Juon kahvia opiskellessani suomea.

You cannot drop -ni if you still want to say “while I study”:

Juon kahvia opiskellessa suomea. – wrong / ungrammatical, missing subject marking

To say “while you study”:

Juot kahvia opiskellessasi suomea.

So the possessive suffix tells who is doing the studying.

Why is suomea in the partitive? Why not suomi?

With opiskella (to study), the thing you study is normally in the partitive case, especially for languages:

opiskella suomea – to study Finnish
opiskella ruotsia – to study Swedish
opiskella englantia – to study English

So suomea is the partitive of suomi (Finnish).

You can think of it as “studying some amount of the language”, an ongoing, not-completed process. That’s why partitive is natural here.

Suomi (nominative) would normally be used as the subject of a sentence:

Suomi on vaikea kieli. – Finnish is a difficult language.

But after opiskella, you use suomea.

Could I say: Minä juon kahvia, kun opiskelen suomea instead of opiskellessani?

Yes.

Minä juon kahvia, kun opiskelen suomea.
Minä juon kahvia opiskellessani suomea.

Both basically mean “I drink coffee when I study Finnish.” / “I drink coffee while studying Finnish.”

Difference in style:

kun opiskelen – more straightforward, easier for learners, commonly used in speech.
opiskellessani – a more compact, slightly more formal or written-style structure, but totally normal.

In everyday speech, many learners (and natives) will prefer:

Juon kahvia, kun opiskelen suomea.

Can I put opiskellessani suomea at the beginning of the sentence?

Yes. Word order is flexible in Finnish. For example:

Opiskellessani suomea juon kahvia. – While I’m studying Finnish, I drink coffee.

This is perfectly grammatical. It puts more focus on the time/circumstance (while I’m studying Finnish).

The meaning is the same; you’re just changing what you emphasize.

What’s the difference between opiskellessani and opiskellen?

Both come from opiskella (to study) but express different nuances:

opiskellessani – 3rd infinitive in inessive + -ni
- Main idea: “while I am studying / when I study” (time/circumstance)
- Links two actions happening at the same time:
  - Juon kahvia opiskellessani suomea. – I drink coffee while I study Finnish.
opiskellen – present active participle (in -en form)
- Often means “by studying” (manner, method):
  - Opin suomea opiskellen joka päivä. – I learn Finnish by studying every day.

So:

opiskellessani = “at the time when I study”
opiskellen = “by means of studying / in a studying way”

They’re not interchangeable in this sentence.

How would I say “when you study Finnish, you drink coffee” using the same structure?

You change the possessive suffix -ni (my) to -si (your) and match the main verb with you:

Sinä juot kahvia opiskellessasi suomea.
- juot = you drink
- opiskellessasi = while you are studying

You can also drop Sinä:

Juot kahvia opiskellessasi suomea.

Or use kun instead:

Juot kahvia, kun opiskelet suomea.

All of these are correct; they just use different structures.

Is opiskellessani a tense? Does it mean “while I was studying” or “while I am studying”?

Opiskellessani itself is not marked for tense. It just expresses simultaneous action: my studying happens at the same time as the main verb.

The tense is decided by the main verb:

Juon kahvia opiskellessani suomea.
- present tense: I drink / I am drinking coffee while I study.
Join kahvia opiskellessani suomea.
- past tense: I drank coffee while I was studying Finnish.

So opiskellessani = “while I (am/was/will be) studying”, and the main verb tells you when in time.

Is opiskellessani something I really need to learn, or can I just always use kun + verb?

You can communicate very well for a long time just using kun + finite verb, for example:

Juon kahvia, kun opiskelen suomea.

However, opiskellessani (and similar forms) are:

Extremely common in written Finnish (books, news, essays).
A natural part of more advanced or compact expression.

You don’t need to master them immediately, but it’s good to recognize them early and gradually learn to use them.

They follow a regular pattern, so once you know one, you can form others:

syödessäni – while I eat
kävellessäni – while I walk
asuuessani (actually asuessani, no double u) – while I live (somewhere)

Understanding opiskellessani is a key step toward reading more natural Finnish.