После пары я зайду в деканат, чтобы уточнить расписание.

Because после requires the genitive case.
The base form is пара, but in the genitive singular it becomes пары.

So:

• пара = a class period / pair
• после пары = after the class period

This is a very common pattern:

• после урока = after the lesson
• после лекции = after the lecture
• после работы = after work

Literally, пара does mean pair, but in student/university speech it often means a class period, especially a longer university block, often about 80–90 minutes.

So после пары usually means:

• after class
• after this class period
• after my lesson

This is very common in Russian student context.

Зайду is the 1st person singular future form of зайти.

In this sentence, it means something like:

• I’ll stop by
• I’ll drop in
• I’ll go in

It often suggests a short visit rather than a long stay. So я зайду в деканат sounds a bit like I’ll stop by the dean’s office.

That nuance is important: it is not just neutral movement, but a brief purposeful visit.

These verbs are related but not identical.

• иду = I am going / I’m on my way now
• пойду = I will go / I’ll set off
• зайду = I will stop by / go in for a moment

In this sentence, the speaker is not just talking about movement in general. They mean they will go into the office briefly for a purpose, so зайду is the most natural choice.

Compare:

• После пары я пойду в деканат = After class I’ll go to the dean’s office.
• После пары я зайду в деканат = After class I’ll stop by the dean’s office.

The second one sounds more natural if the visit is short and practical.

That is because зайти is a perfective verb.

In Russian, perfective verbs do not have a true present tense. Their present-looking forms actually refer to the future:

• я зайду = I will stop by
• ты зайдёшь = you will stop by
• он зайдёт = he will stop by

So although the form resembles a present-tense conjugation pattern, the meaning is future.

Because the sentence expresses motion into a place, and with verbs of motion Russian often uses:

• в + accusative = into / to
• на + accusative = onto / to

Here, деканат is masculine inanimate, and its accusative form is the same as the nominative:

• деканат → в деканат

So:

• зайти в деканат = to go into / stop by the dean’s office

Compare with location:

• я в деканате = I am in the dean’s office

That would use the prepositional case, because it describes location, not motion.

Деканат is the administrative office of a faculty or department at a university, connected with the dean’s administration.

A natural English translation depends on context:

• the dean’s office
• the faculty office
• the department administration office

It usually does not mean the dean personally; it means the office where administrative matters are handled.

Чтобы introduces a purpose clause. It often means:

• in order to
• so that
• to

So:

• я зайду в деканат, чтобы уточнить расписание = I’ll stop by the dean’s office to clarify the schedule
  = I’ll stop by the dean’s office in order to clarify the schedule

This is one of the most common uses of чтобы.

Уточнить means to clarify, to verify, to make more precise.

It suggests that the speaker already has some information, but wants to check or refine it.

• уточнить расписание = clarify / confirm the schedule

By contrast, узнать means to find out or to learn something new.

So the difference is roughly:

• узнать расписание = find out what the schedule is
• уточнить расписание = confirm or clarify the schedule details

If the speaker already knows the schedule but thinks something may have changed, уточнить is a very good choice.

Here расписание is in the accusative case, because it is the direct object of уточнить.

The dictionary form is also расписание, and because it is a neuter inanimate noun, the nominative and accusative look the same:

• nominative: расписание
• accusative: расписание

So the form does not change, even though the case does.

Yes, very often it could.

Russian frequently omits subject pronouns when the verb ending already shows who the subject is. Since зайду clearly means I will, you could say:

• После пары зайду в деканат, чтобы уточнить расписание.

This is perfectly natural.

Including я can add:

• emphasis
• contrast
• clarity

In this sentence, я is not wrong at all; it is just slightly more explicit.

Yes, Russian word order is fairly flexible.

The sentence as given is neutral and natural:

• После пары я зайду в деканат, чтобы уточнить расписание.

But other orders are possible, for example:

• Я после пары зайду в деканат, чтобы уточнить расписание.
• В деканат я зайду после пары, чтобы уточнить расписание.

The basic meaning stays the same, but the emphasis changes:

• После пары first emphasizes the time
• в деканат first emphasizes the destination
• я first can emphasize the subject

So the original sentence is a very normal, neutral way to say it.

Yes. After чтобы, Russian often uses an infinitive when the subject is understood from the main clause.

Here, the person who will stop by is the same person who wants to clarify the schedule, so Russian naturally uses the infinitive:

• я зайду ..., чтобы уточнить ...

This is similar to English:

• I’ll stop by ... to clarify ...

If the subject were different, Russian would usually use a finite verb instead of just the infinitive.

Yes, depending on context.

• после урока = after the lesson
• после занятий = after classes
• после пары = after the class period

После пары sounds especially natural in a university/student setting.
A school student would more often say после урока.
If you mean after all classes for the day, после занятий may fit better.

So после пары is correct, but it reflects a particular academic context.

The main stresses are:

• После па́ры
• я зайду́
• в декана́т
• что́бы уточни́ть
• расписа́ние

A rough pronunciation guide:

• После = POS-le
• па́ры = PA-ry
• зайду́ = zai-DOO
• декана́т = de-ka-NAT
• уточни́ть = oo-tach-NEET
• расписа́ние = ras-pee-SA-ni-ye

The stress matters a lot in Russian, so it is worth learning each word together with its stressed syllable.