Learn Hardcore Finnish: Mitä useammin opiskelen suomea, sitä helpompaa se on. - The more often I study Finnish, the easier it is.

Mitä useammin opiskelen suomea
→ literally: what (the) more often I study Finnish…
→ English-like idea: the more often I study Finnish…
sitä helpompaa se on
→ literally: that (the) easier it is
→ English-like idea: the easier it is.

So you can think of it as:

Mitä = “the (more)” in the first half
sitä = “the (more)” in the second half

Used together with comparatives, they form:
Mitä + comparative…, sitä + comparative… = The more…, the more…

Why is it Mitä useammin and not just Useammin?

You could say simply Useammin opiskelen suomea, sitä helpompaa se on, and people would understand, but it sounds less natural and weaker.

The mitä:

marks the first half of the correlative pair (mitä – sitä),
emphasizes the comparative idea: “the more often…” rather than just “more often…”,
is part of a very common and idiomatic pattern:
Mitä + comparative, sitä + comparative.

So Mitä useammin is not a question; it’s the first half of this special pattern that sets up the comparison.

What case is mitä in here, and why that case?

Mitä here is the partitive singular of mikä (“what”).

In this correlative structure, Finnish uses the partitive form:

Mitä (partitive of mikä) in the first clause
sitä (partitive of se) in the second clause

This partitive is tied to the idea of degree/amount and to the comparative, and it’s simply how this construction is formed in standard Finnish. You don’t change it to nominative (mikä, se) or genitive (minkä, sen) in this pattern; it’s mitä – sitä by rule.

Why is it sitä helpompaa, not sen helpompi or just helpompi?

Two things are going on:

sitä
- This is the partitive of se (“it/that”).
- It forms the fixed pair with mitä: mitä – sitä.
- Using sen (genitive) here would be ungrammatical in this structure.
- So you must say: Mitä X, sitä Y (both in partitive).
helpompaa
- This is the partitive singular of the comparative adjective helpompi (“easier”).
- It’s a predicative (it describes the subject se): “it is easier”.
- In this correlative construction, Finnish very often puts the predicative in partitive to express a gradual / open-ended degree of the quality:
  - sitä helpompaa (se on) = the easier (it gets / it is – to whatever extent)

You can see helpompi in other contexts as a predicative:

Tämä tehtävä on helpompi. = This task is easier.

But with sitä + comparative in this “the more…the more” structure, partitive (helpompaa) is by far the most natural choice.

Why is helpompaa in the partitive case at all? I thought predicative adjectives usually match the subject in case.

Predicative adjectives often appear in nominative (e.g. Se on helppo – “It is easy”), but they can also be in partitive for semantic reasons.

Partitive predicative is used, among other things, when:

the quality is seen as gradual, not fully delimited, or a matter of degree,
we talk about something that is becoming more or less something, or its degree can change.

In this sentence:

sitä helpompaa se on
expresses a degree of easiness that changes as you study more often.
It’s not a yes/no “it is easy”; it’s a “more and more easy” kind of idea.

So helpompaa (partitive) fits the meaning of a gradually increasing quality in this comparative structure.

Could the sentence be Mitä useammin opiskelen suomea, sitä helpompi se on with helpompi (nominative)?

You might hear sitä helpompi se on in speech, and it’s not shocking, but:

sitä helpompaa se on (partitive) is definitely more natural and idiomatic in this construction.
The partitive aligns better with the idea of degree / “more and more easy”.

So while helpompi wouldn’t be completely incomprehensible, helpompaa is what you should learn and use here.

Why is it suomea and not suomi after opiskelen?

Suomea is the partitive singular of suomi (“Finnish” as a language).

After opiskella (“to study [an academic subject / language]”), the object is typically in the partitive when you mean studying the subject in general:

Opiskelen suomea. = I study Finnish (in general, as a subject).
Opiskelen matematiikkaa. = I study mathematics.

Using suomi (nominative) here would sound unidiomatic or wrong. For languages as study subjects, partitive is the default object case with opiskella.

What is the difference between opiskelen suomea and something like opin suomea?

Both relate to learning, but:

opiskella = to study (actively, often systematically, as a student)
- Opiskelen suomea. = I study Finnish (do exercises, take classes, etc.)
oppia = to learn (come to know/understand something)
- Opin suomea nopeasti. = I learn Finnish quickly.

In your sentence, the focus is on the studying activity/frequency, so opiskelen suomea (“I study Finnish”) is exactly what you want.
If you said Mitä useammin opin suomea, it would sound strange, as if you repeatedly “come to learn Finnish” many times; the verb doesn’t fit that repetitive, ongoing action idea.

Can I change the word order, for example: Sitä helpompaa se on, mitä useammin opiskelen suomea?

Yes. That is perfectly grammatical and natural:

Sitä helpompaa se on, mitä useammin opiskelen suomea.

Word order here mainly affects emphasis:

Mitä useammin opiskelen suomea, sitä helpompaa se on.
→ slightly more focus on the condition (how often you study).
Sitä helpompaa se on, mitä useammin opiskelen suomea.
→ slightly more focus on the result (that it is easier).

Both orders are used; both are correct.

Why is there a comma in the middle? Is this two full sentences?

It’s one complex sentence with two clauses:

Mitä useammin opiskelen suomea,
sitä helpompaa se on.

The comma marks the boundary between the two correlated clauses in the mitä – sitä structure.

In spoken Finnish, this is usually reflected by a small pause and often a slight change in intonation between the halves, similar to how you say in English:

The more often I study Finnish, (pause) the easier it is.

Do mitä and sitä here have their normal meanings “what” and “that/it”, or are they just grammatical markers?

They started life as “what” (mitä) and “that/it” (sitä), but in this construction they behave mostly like grammatical markers for the correlative pattern.

You can still think of a faint literal idea:

Mitä useammin… ≈ to whatever (degree) more often…
sitä helpompaa… ≈ to that same (degree) easier…

But for practical learning, it’s best to treat mitä – sitä here as a fixed comparative pair, just like English has the fixed “the more – the more” (where “the” is also not the usual article).

Can I leave out se and just say sitä helpompaa on?

You sometimes hear sitä helpompaa on in casual speech, and people will understand. However:

sitä helpompaa se on
is clearer and more standard because it explicitly has the subject se (“it”).

Dropping se is more colloquial and can sound slightly incomplete in careful written language. As a learner, it’s safer and better style to keep the se.

Is this structure mitä – sitä used only with adverbs like useammin, or also with adjectives and other comparatives?

It’s used with a wide range of comparatives, both adjectives and adverbs. A few examples:

Mitä vanhemmaksi tulen, sitä viisaammaksi tulen.
= The older I get, the wiser I become.
Mitä nopeammin teet sen, sitä parempi.
= The faster you do it, the better.
Mitä enemmän harjoittelet, sitä vahvemmaksi tulet.
= The more you practice, the stronger you become.
Mitä pidempi matka on, sitä väsyneempi olen.
= The longer the trip is, the more tired I am.

So the pattern is very productive: Mitä + comparative…, sitä + comparative… across many types of words.

Can I express the same idea without using the mitä – sitä structure?

Yes. You can rewrite the sentence in a more “ordinary” conditional/temporal way, for example:

Kun opiskelen suomea useammin, se on helpompaa.
= When I study Finnish more often, it is easier.
Jos opiskelen suomea useammin, se on helpompaa.
= If I study Finnish more often, it is easier.

These are fully correct and understandable.
However, Mitä useammin opiskelen suomea, sitä helpompaa se on is more idiomatic and elegant for this exact “the more…, the more…” meaning.