Learn Hardcore Finnish: Opettaja muistuttaa, että jokaisella on oikeus kysyä, jos jokin asia on epäselvä. - The teacher reminds us that everyone has the right to ask if something is unclear.

In your sentence, muistuttaa is used in the “remind” sense, followed by an että-clause that tells what the teacher reminds us of. The person being reminded (e.g. oppilaita, the students) is omitted because it’s clear from context.

Why is there a comma before että and before jos?

In Finnish, you normally put a comma before most subordinate clauses, including those starting with:

että (that)
jos (if)
kun, koska, jotta, etc.

So:

Opettaja muistuttaa, että jokaisella on oikeus kysyä…
…kysyä, jos jokin asia on epäselvä.

Both että jokaisella on oikeus… and jos jokin asia on epäselvä are subordinate clauses, so they are separated from the main clause with a comma.

Why is it jokaisella and not jokainen?

Finnish typically shows possession with the verb olla and the possessor in the adessive case (-lla/-llä):

Minulla on kynä. – I have a pen. (literally: On me is a pen.)
Kaikilla on kysymyksiä. – Everyone has questions.

The same pattern is used here:

jokaisella = on every one / everyone has
on oikeus = there is a right / (someone) has the right

So:

Jokaisella on oikeus kysyä. – Everyone has the right to ask.

Jokainen on oikeus kysyä would be incorrect, because jokainen (nominative) is not the form used for the possessor in this construction.

What does oikeus kysyä literally mean, and why is kysyä in the basic infinitive?

Oikeus = right (in the legal/moral sense)
kysyä = basic (1st) infinitive of to ask

The pattern is:

olla oikeus + infinitive = to have the right to do something

Examples:

Minulla on oikeus äänestää. – I have the right to vote.
Sinulla on oikeus tietää. – You have the right to know.

So oikeus kysyä = the right to ask.
The basic infinitive kysyä is used here, not a nominal form like kysyminen, because Finnish very often uses infinitive 1 after nouns like oikeus, mahdollisuus, halu, etc.:

mahdollisuus oppia – a chance to learn
halu auttaa – a desire to help

Why is it jokaisella on oikeus kysyä and not something like jokainen saa kysyä?

Both are grammatical, but they don’t mean exactly the same:

Jokaisella on oikeus kysyä
- Focuses on right or entitlement (moral/legal/official right).
- Sounds slightly more formal or rule-like.
Jokainen saa kysyä
- saa = may, is allowed to.
- Focuses more on permission from someone (e.g. the teacher).

In a classroom context, jokaisella on oikeus kysyä emphasises that asking questions is a basic, legitimate right of every student, not just some permission that could be withdrawn arbitrarily.

What is the difference between jokin and joku? Why jokin asia here?

Both are indefinite pronouns:

joku – usually for people (someone, somebody, a certain person)
jokin – usually for things (something, some thing, some matter)

Examples:

Joku koputtaa oveen. – Someone is knocking on the door. (a person)
Jokin on vialla. – Something is wrong. (a thing/situation)
Jokin asia on epäselvä. – Some matter/thing is unclear.

In your sentence, we are talking about a thing / matter that is unclear, not a person, so jokin is correct:

jos jokin asia on epäselvä – if some matter/anything is unclear

Why do we say jokin asia on epäselvä and not jokin asia on epäselvää?

Both epäselvä and epäselvää can appear with olla, but they have different uses.

Here:

jokin asia is a specific singular noun phrase.
It’s the subject of the verb on.
The complement (predicative) agrees with it in number and case:
- Asia on epäselvä. – The matter is unclear.

So:

jokin asia on epäselvä – some particular matter is unclear.

If you said:

On epäselvää, onko se totta. – It is unclear whether that is true.

Here epäselvää is in the partitive, describing an unspecified, general state, and there is no concrete noun like asia as subject. That’s why in your sentence, with a clear subject jokin asia, we use nominative epäselvä.

Why is there no object after kysyä? Shouldn’t it be kysyä kysymyksiä or something?

Finnish often allows verbs like kysyä (to ask) without an explicit object when it’s obvious from context:

Voit aina kysyä. – You can always ask (a question).
Onko teillä kysyttävää? Voitte kysyä. – Do you have anything to ask? You can ask.

In your sentence:

jokaisella on oikeus kysyä – everyone has the right to ask

It’s understood that this means to ask questions or to ask the teacher, so there is no need to add kysymyksiä or opettajalta unless you want to be more explicit.

You could say:

Jokaisella on oikeus kysyä kysymyksiä.
but it’s not necessary.

Can the word order in jos jokin asia on epäselvä be changed?

Yes, Finnish word order is flexible, especially inside subordinate clauses. These are all grammatical:

jos jokin asia on epäselvä (neutral, like your sentence)
jos asia on jokin epäselvä (odd; usually avoid splitting jokin asia)
jos asia on epäselvä (drops jokin, meaning if the matter is unclear)

You can also move the clause:

Jos jokin asia on epäselvä, jokaisella on oikeus kysyä.
Jokaisella on oikeus kysyä, jos jokin asia on epäselvä.

Both orders are natural. Starting with the jos-clause can slightly emphasise the condition.

Is there any difference in nuance between jokin asia and just jokin in this context?

Yes, a small nuance:

jokin asia – literally some thing / some matter
- Slightly clearer and more concrete.
- Common in spoken and written language: jos jokin asia on epäselvä.
jokin alone – often more abstract or general:
- jos jokin on epäselvää – if something is unclear (more vague, no explicit asia)

In teaching or instructions, jokin asia sounds reassuring and student-friendly: it suggests any topic, point, detail, or step that might be unclear.