Learn Hardcore Finnish: Kansiosta löytyi kaikki, mitä jaoimme eilen. - In the folder we found everything that we shared yesterday.

So kansiosta is chosen because Finnish says literally “from the folder was found…”, not “in the folder was found…”, even though English usually just says “in the folder”.

What exactly is löytyi, and how is it different from löytää or oli?

löytyä = to be found, to turn up (intransitive verb)
löytyi = past tense, 3rd person singular of löytyä

So löytyi means “was found / turned up / could be found”.

Compare:

löytää = to find (transitive)
- Löysin tiedoston. = I found the file.
löytyä = to be found (intransitive)
- Tiedosto löytyi kansiosta. = The file was found in the folder.

oli just means “was” and doesn’t contain the idea of finding.
löytyi implies that the things either turned up or were available/locatable, often after some search or checking.

Why is it löytyi (singular) when kaikki seems plural (“all the things”)?

In sentences like this, Finnish uses a structure called an existential sentence:

Kansiosta löytyi kaikki.
Place (kansiosta) + verb (löytyi) + new thing (kaikki)

In such sentences:

The verb is usually 3rd person singular, regardless of how many items there are.
The noun phrase after the verb (kaikki) is the logical subject, but its number doesn’t force the verb to plural here.

Also, kaikki can be understood as:

“everything” (grammatically singular mass)
or “all (the things)” (plural in meaning)

In this structure, Finnish defaults to singular: löytyi, not löytyivät, even though löytyivät is also grammatically possible and would emphasize the plurality more:

Kansiosta löytyivät kaikki tiedostot. = All the files were found in the folder.

Is the basic word order here Kansiosta löytyi kaikki? Could I also say Kaikki löytyi kansiosta?

Both are possible, but the emphasis changes.

Kansiosta löytyi kaikki.
→ Typical existential order: From the folder was found everything.
→ Emphasizes the place first, then introduces what was there as new information.
Kaikki löytyi kansiosta.
→ Subject-like element first: Everything was found in the folder.
→ Emphasizes everything more strongly; the place is secondary.

In your original sentence, putting kansiosta first matches the common Finnish pattern: “In/from X there was Y / Y was found.” It is especially natural if the folder is already known in the context (and the “everything” is the new piece of information).

Why is there a comma before mitä in kaikki, mitä jaoimme eilen?

Finnish uses commas to separate subordinate clauses, including relative clauses that describe a noun.

Here, mitä jaoimme eilen is a relative clause describing kaikki:

kaikki, mitä jaoimme eilen = everything that we shared yesterday

Because mitä jaoimme eilen gives extra information about kaikki, Finnish rules require a comma before it. This is not optional here; it’s part of standard punctuation.

What is the role of mitä jaoimme eilen in the sentence?

mitä jaoimme eilen is a relative clause that modifies kaikki. Together they form:

kaikki, mitä jaoimme eilen = everything (that) we shared yesterday

Structure:

mitä → relative pronoun, referring back to kaikki
jaoimme → past tense, 1st person plural (we shared)
eilen → adverb of time (yesterday)

So the core sentence is:

Kansiosta löytyi kaikki. = Everything was found in the folder.

And mitä jaoimme eilen narrows down what everything refers to: not just any “everything”, but specifically “everything that we shared yesterday”.

Why is the relative word mitä and not jota or jotka?

Finnish has several relative words: joka, mikä, mitä, etc.
In this particular pattern, kaikki, mitä … is very common and idiomatic.

General tendencies:

joka / jota / jotka: more concrete, often with a clearly countable noun.
mikä / mitä: often with indefinite words like kaikki (all, everything), se (that which), paljon (much), etc.

So:

kaikki, mitä jaoimme eilen
= everything that we shared yesterday
(very natural, default phrasing)

Using joka-forms would be less typical here. You might see kaikki, jotka jaoimme eilen, but it sounds more like discrete, clearly countable items and is less idiomatic than kaikki, mitä… in this kind of sentence.

In practice, when you have kaikki meaning “everything”, follow it with mitä:

kaikki, mitä haluat = everything (that) you want
kaikki, mitä tarvitset = everything (that) you need

Why is mitä in that form (partitive)? What is it agreeing with?

mitä is the partitive form of the relative pronoun mikä.

The combination kaikki, mitä … tends to use mitä (partitive), not mikä (nominative):

kaikki, mitä…
se, mitä…
paljon, mitä…

This is partly idiomatic and partly connected to the idea of an indefinite mass/amount rather than a specific, countable set. kaikki here is closer to “everything” (mass) than to “all the individual items”.

You do not have to “force” an agreement here the way you might in English; you simply learn the pattern:

kaikki, mitä + verb is the normal way to say “everything that …” in Finnish.

How does jaoimme work grammatically?

jaoimme is the past tense of jakaa (to share, also to divide), conjugated in 1st person plural:

Infinitive: jakaa = to share
Present, we: jaamme = we share
Past, we: jaoimme = we shared

Breakdown of jaoimme:

jako- (past stem)
-i- (past tense marker)
-mme (ending for we)

Finnish usually omits the pronoun when the verb ending already shows the person, so me jaoimme (we shared) → jaoimme is enough.

Why is eilen at the end? Could it go somewhere else?

eilen means “yesterday”. Finnish has quite flexible word order for adverbs of time.

All of these are grammatically possible:

Kansiosta löytyi kaikki, mitä jaoimme eilen.
Kansiosta löytyi eilen kaikki, mitä jaoimme.
Eilen kansiosta löytyi kaikki, mitä jaoimme.

However:

Putting eilen at the end of the relative clause (mitä jaoimme eilen) is very natural, neutral Finnish: [what we shared yesterday].
Moving eilen earlier changes emphasis or slightly disrupts the tight unit mitä jaoimme eilen.

In your sentence, eilen at the end keeps the relative clause smooth and clear.

Is kaikki the subject or the object in this sentence?

Grammatically in Finnish, kaikki in:

Kansiosta löytyi kaikki, mitä jaoimme eilen.

functions as the subject of löytyi.

This is an existential construction:

[Place] + löytyi + [new thing]

In such sentences, the new thing (here kaikki) is the subject, even though in English it may feel more like an object:
From the folder was found everything…

If you flip the order:

Kaikki, mitä jaoimme eilen, löytyi kansiosta.

it becomes easier to see that kaikki is subject-like. It is in the nominative form (not partitive, not object case), which is one sign that it’s functioning as a subject.

Could I say Kaikki, mitä jaoimme eilen, löytyi kansiosta instead? Does it mean the same thing?

Yes, that sentence is perfectly correct:

Kaikki, mitä jaoimme eilen, löytyi kansiosta.

Meaning-wise it matches the original. The difference is mainly word order and emphasis:

Kansiosta löytyi kaikki, mitä jaoimme eilen.
→ Starts with the folder; emphasizes where the things were found.
Kaikki, mitä jaoimme eilen, löytyi kansiosta.
→ Starts with everything; emphasizes that all of that material ended up in the folder.

Both are natural; the choice depends on what you want to highlight in the context.

Can I leave out kaikki and just say Kansiosta löytyi, mitä jaoimme eilen?

No, that would be incorrect.

You need a noun or pronoun for the relative clause mitä jaoimme eilen to refer back to. In this construction, kaikki is that head word:

kaikki, mitä jaoimme eilen = everything that we shared yesterday

Without kaikki, mitä jaoimme eilen is left “hanging” with nothing to describe. So you must keep kaikki (or another appropriate word, like se):

Kansiosta löytyi kaikki, mitä jaoimme eilen.
Kansiosta löytyi se, mitä jaoimme eilen.

How else could I say this idea in Finnish, using slightly different wording?

Here are a few natural alternatives with similar meaning, just phrased differently:

Kaikki eilen jakamamme tiedostot löytyivät kansiosta.
- All the files that we shared yesterday were found in the folder.
  (Here jakamamme tiedostot = “the files we shared”.)
Kansiosta löytyivät kaikki ne asiat, jotka jaoimme eilen.
- From the folder were found all those things that we shared yesterday.
Kansiosta löytyi kaikki eilen jakamamme materiaali.
- All the material that we shared yesterday was found in the folder.

These show some common tools: participle forms like jakamamme (“that we shared”) and the relative pronoun jotka, but the core idea remains the same as in the original sentence.