Learn Hardcore Greek: Πριν φύγουμε από την τάξη, η δασκάλα μάζευε τα διαγωνίσματα και έλεγχε πόση ώρα διήρκεσε η εξέταση. - Before we left the classroom, the teacher collected the tests and checked how long the exam had lasted.

Πριν φύγαμε is ungrammatical in standard Modern Greek in this structure. The event is in the past, but the tense is shown by the whole sentence context, not by using the indicative here; the conjunction πριν demands the subjunctive.

Why is there no να after πριν? Can I say πριν να φύγουμε?

Both are heard:

Πριν φύγουμε, ...
Πριν να φύγουμε, ...

In contemporary standard Greek:

Πριν φύγουμε is the more neutral and more common form, especially in writing.
Πριν να φύγουμε is also used, but often sounds more colloquial or regional. Some style guides discourage it, but many native speakers use it naturally.

So your sentence is perfectly natural as Πριν φύγουμε από την τάξη, ... and does not need να.

Why is φύγουμε in the aorist subjunctive and not present subjunctive (φεύγουμε)?

Greek subjunctive has aspect (aorist vs present), not tense (past vs non‑past).

φεύγουμε (present subjunctive) would focus on a leaving that is ongoing or repeated.
φύγουμε (aorist subjunctive) focuses on the whole event as a single, complete action.

Here, leaving the classroom is seen as a single event that marks a boundary in time:

Πριν φύγουμε από την τάξη...
= Before the event of us leaving the classroom...

Using φεύγουμε would sound odd in this context, as if talking about a process or a repeated habit.

Why is μάζευε used, not μάζεψε? What is the difference?

Both come from μαζεύω (to gather, to collect):

μάζευε = imperfect, she was collecting (ongoing background action)
μάζεψε = aorist, she collected (one completed event)

In your sentence:

η δασκάλα μάζευε τα διαγωνίσματα
= the teacher was collecting the tests (in progress at that time)

The imperfect μάζευε paints the scene: while the class was about to leave, the action of collecting was ongoing.

If you said:

Πριν φύγουμε από την τάξη, η δασκάλα μάζεψε τα διαγωνίσματα.

it would mean:

Before we left the classroom, the teacher collected the tests (completed action before the leaving).

So the original uses the imperfect to describe background, continuous action around the moment of leaving.

Similarly, why do we have έλεγχε and not έλεγξε?

Same aspect contrast:

έλεγχε (from ελέγχω) = imperfect, she was checking
έλεγξε = aorist, she checked (completed)

In the sentence:

...η δασκάλα μάζευε τα διαγωνίσματα και έλεγχε πόση ώρα διήρκεσε η εξέταση.

Both actions μάζευε and έλεγχε are background processes happening around that time. That is why the imperfect is chosen.

If you used έλεγξε, you would focus on a finished checking, not on an activity in progress.

Why is it από την τάξη and not something like a genitive form (as in older Greek)?

In Modern Greek, almost all prepositions are followed by the accusative case.

So:

από
- accusative: από την τάξη = from the classroom

Classical/ancient Greek often used genitive after certain prepositions, but modern usage has simplified this. With από, you just learn it as:

από
- accusative (always, in modern standard Greek)

What is the difference between διαγώνισμα and εξέταση here? They both seem to mean “exam”.

They are related but not identical in nuance:

το διαγώνισμα
- usually: a test, quiz, or exam paper in a school context
- concrete: the specific sheet or classroom test the teacher collects
η εξέταση
- more general: examination as a process or event
- used for school/university exams, medical examinations, etc.

In the sentence:

μάζευε τα διαγωνίσματα = she was collecting the actual test papers
πόση ώρα διήρκεσε η εξέταση = how long the exam session / examination lasted

So διαγώνισμα is the individual test; εξέταση is the overall event.

Why πόση ώρα and not πόσο χρόνο for “how long”?

Both exist, but πόση ώρα is the most natural, everyday way to ask how long (in time) something lasted:

Πόση ώρα διήρκεσε; = How long did it last?

πόσο χρόνο is also grammatically correct, but is:

less idiomatic in this fixed phrase
often used when you emphasize the amount of time as a resource, e.g. Δεν έχω πολύ χρόνο (I do not have much time).

Here, πόση ώρα is the standard collocation with διήρκεσε.

Why is it διήρκεσε and not something like διαρκούσε?

Both come from διαρκώ (to last):

διήρκεσε = aorist, it lasted (viewed as a completed whole)
διαρκούσε = imperfect, it was lasting / it used to last (ongoing or repeated)

In πόση ώρα διήρκεσε η εξέταση:

the exam is seen as a finished event with a measurable total duration → aorist διήρκεσε is natural.

πόση ώρα διαρκούσε η εξέταση would sound like:

How long was the exam lasting?
It could work in some narrative contexts, but for a simple question about total duration, Greek prefers the aorist διήρκεσε.

Why is the word order πόση ώρα διήρκεσε η εξέταση and not η εξέταση διήρκεσε πόση ώρα in this indirect question?

In Greek, clauses introduced by a question word (like πόσος, πού, πότε) keep question-like word order even when they are indirect questions.

Direct question: Πόση ώρα διήρκεσε η εξέταση;
Indirect: ...έλεγχε πόση ώρα διήρκεσε η εξέταση.

So the structure with πόση ώρα first is completely natural.

The variant ...έλεγχε η εξέταση διήρκεσε πόση ώρα is not natural Greek. You can sometimes move elements around for emphasis, but with πόση ώρα you normally keep it at the front.

Could the sentence be Η δασκάλα μάζευε τα διαγωνίσματα πριν φύγουμε από την τάξη instead? Is that meaningfully different?

Yes, that word order is also correct:

Πριν φύγουμε από την τάξη, η δασκάλα μάζευε τα διαγωνίσματα...
Η δασκάλα μάζευε τα διαγωνίσματα πριν φύγουμε από την τάξη...

Both mean essentially the same: Before we left the classroom, the teacher was collecting the tests...

Differences:

Placing Πριν φύγουμε από την τάξη at the beginning slightly sets the time frame first, like a scene‑setting phrase.
Putting πριν φύγουμε από την τάξη later sounds a bit more neutral in spoken language.

Semantically, they are equivalent; it is mostly a matter of style and emphasis.

What are the present tense forms of the verbs φεύγω, μαζεύω, ελέγχω, διαρκώ in the relevant persons?

Relevant present forms (first person plural and third person singular):

φεύγω
- εμείς φεύγουμε = we leave / we are leaving
μαζεύω
- η δασκάλα μαζεύει = the teacher collects / is collecting
ελέγχω
- η δασκάλα ελέγχει = the teacher checks / is checking
διαρκώ
- η εξέταση διαρκεί = the exam lasts / is lasting

In your sentence, the past forms are:

φύγουμε (aorist subjunctive)
μάζευε (imperfect)
έλεγχε (imperfect)
διήρκεσε (aorist)

Are τάξη, δασκάλα, and εξέταση all feminine nouns? How do the articles match?

Yes, all three are feminine in Modern Greek:

η τάξη (class, classroom)
- accusative singular: την τάξη → από την τάξη
η δασκάλα (female teacher, mostly for primary school)
- nominative singular: η δασκάλα → subject of the verb
η εξέταση (examination, exam)
- nominative singular: η εξέταση → subject of διήρκεσε

The definite article always agrees in gender, number, and case:

η (nom. sg. fem.) for η δασκάλα, η εξέταση
την (acc. sg. fem.) for την τάξη