Learn Hardcore Greek: Όταν ήσουν στο σχολείο, εγώ έτρωγα έξω. - When you were at school, I was eating out.

Because έτρωγα (imperfect) presents the action as ongoing or habitual in the past: “I was eating / I used to eat.” With όταν ήσουν… the time frame is backgrounded, so the imperfect fits well. Έφαγα (aorist) is a single, completed event (“I ate”). You could say aorist for a one-off event, but then you’d normally mark that contextually, e.g. Ενώ ήσουν στο σχολείο, έφαγα έξω (“While you were at school, I ate out [once]”).

Is the subject pronoun εγώ necessary?

No. Greek is a pro‑drop language. Έτρωγα έξω is perfectly fine and more neutral. Adding εγώ adds emphasis or contrast: “I (as opposed to someone else) was eating out.”

Can I swap the clause order or remove the comma?

Yes. Two common options:

Όταν ήσουν στο σχολείο, εγώ έτρωγα έξω. (Subordinate clause first → comma.)
Εγώ έτρωγα έξω όταν ήσουν στο σχολείο. (Main clause first → typically no comma.)

What exactly is στο in στο σχολείο?

Στο is the contraction of σε + το (“in/at” + “the” neuter). Similar contractions:

σε + τα → στα (e.g., στα σχολεία)
σε + την → στην (e.g., στην τάξη; often στη before certain consonants)

Why do I sometimes see no article with “school,” as in πάω σχολείο?

With verbs of motion and certain institutions, Greek often drops the article to mean the general activity:

Πάω σχολείο / δουλειά / εκκλησία. But with “being/located” or when specific, you use the article:
Είμαι στο σχολείο.
Πάω στο καινούριο σχολείο.

Does the sentence describe a single time or a habit?

With the imperfect (έτρωγα), it can be either:

Ongoing at a particular past time (“I was eating out then”).
Habitual (“Whenever you were at school, I used to eat out.”) Context or adverbs clarify: συχνά, κάθε μέρα for habitual; aorist (έφαγα) plus time markers for a single event.

What’s the difference between όταν, ενώ, καθώς, and όσο here?

Όταν: neutral “when,” for single or repeated times.
Ενώ: “while/whereas,” often adds contrast between two actions/states.
Καθώς: “as/while,” highlights simultaneity of ongoing actions.
Όσο: “as long as/while,” emphasizes duration/extent.

Is ήσουνα also correct for “you were”?

Yes, ήσουνα is a common colloquial variant of ήσουν. In formal writing, prefer ήσουν. Similarly, you’ll see ήταν / ήτανε for “he/she/it was.” Avoid nonstandard forms like ήσουνε for 2nd singular.

How do you pronounce the sentence?

Stressed syllables are marked in bold below; IPA given in brackets:

Όταν [ˈotan]
ήσουν [ˈisun]
στο [sto]
σχολείο [sxoˈlio]
εγώ [eˈɣo] (the γ is a soft “gh,” like Spanish in lago)
έτρωγα [ˈetroɣa]
έξω [ˈekso] Natural flow: [ˈotan ˈisun sto sxoˈlio eˈɣo ˈetroɣa ˈekso]

What are the full imperfect (past continuous) forms of τρώω and είμαι?

Τρώω (imperfect): έτρωγα, έτρωγες, έτρωγε, τρώγαμε, τρώγατε, έτρωγαν / τρώγαν(ε).
Είμαι (imperfect): ήμουν, ήσουν, ήταν / ήτανε, ήμασταν (also ήμαστε), ήσασταν (also ήσαστε), ήταν / ήτανε.

Is τρώω εκτός a valid way to say “eat out”?

No. Use τρώω έξω or βγαίνω για φαγητό. Εκτός doesn’t mean “out (to a restaurant)” in this context.

Can I use θα inside an όταν-clause?

Normally no. For future time, Greek uses present in the όταν-clause and θα in the main clause:

Όταν πας στο σχολείο, θα φάω έξω. (single future event)
Όταν πηγαίνεις στο σχολείο, θα τρώω έξω. (habitual/ongoing in the future)

Where can έξω go in the sentence?

Default is after the verb: έτρωγα έξω. You can front it for emphasis: Έξω έτρωγα (focusing on location), but the neutral placement is after the verb.

Do capital letters keep the accent in Greek, as in Όταν?

Yes. In standard modern Greek orthography, uppercase vowels retain the accent mark: Όταν, Έξω, Ήσουν.

Why is σχολείο in that form after σε/στο?

Greek prepositions (like σε) take the accusative case. Σχολείο is neuter; its nominative and accusative singular have the same form, so you don’t see a change. With other genders you do: στον φίλο (masc. acc.), στην τάξη (fem. acc.).