Learn Hardcore Croatian: Učitelj trči s djecom poslije škole. - The male teacher runs with the children after school.

Because the preposition s/sa meaning with takes the instrumental case. The noun djeca (children) becomes djecom in the instrumental plural. So: s djecom = with the children.

What case is djecom, and how does djeca decline?

Djecom is instrumental plural. The irregular plural of dijete (child) is djeca (children). Key forms:

Nominative: djeca (children)
Genitive: djece
Dative/Locative: djeci
Accusative: djecu
Vocative: djeco
Instrumental: djecom

With s/sa = with, use instrumental: s djecom.

When do I use s vs sa?

Both mean with. s is the default. sa is used for easier pronunciation, especially before words starting with s, z, š, ž or tricky clusters (e.g., sa psom, sa sestrom). Here, both s djecom and sa djecom are acceptable; s djecom is perfectly natural.

Could I write s decom instead of s djecom?

That’s a dialect/standard difference. S decom is the Serbian ekavian form; standard Croatian uses the ijekavian form s djecom. Stick with djecom in Croatian.

Why is it poslije škole? What case does poslije require?

Poslije (after) is a preposition that takes the genitive case, so škola becomes genitive singular škole. Synonyms:

nakon škole (also genitive)
More colloquial/regional: posle škole (not standard Croatian spelling)

Is trči “runs” or “is running”? Croatian doesn’t have a separate present continuous, right?

Correct. Croatian present covers both:

Habitual: He runs with the children after school.
Ongoing: He is running with the children after school (e.g., today). Context or adverbs clarify it: obično (usually) vs sada (now).

What’s the verbal aspect of trčati, and what are common perfective partners?

Trčati is imperfective (ongoing/habitual). Common perfectives:

potrčati = to start running
istrčati = to run out / to complete a run
otrčati = to run off Choose based on meaning; for simple “running” as an activity, trčati is right.

Can I change the word order?

Yes; Croatian word order is flexible. Examples (all correct, with different emphasis):

Učitelj trči s djecom poslije škole. (neutral)
Poslije škole učitelj trči s djecom. (time in focus)
Učitelj poslije škole trči s djecom. (still natural) Keep related elements together for clarity.

What’s the difference between učitelj, nastavnik, and profesor?

učitelj/učiteljica: typically primary/elementary school teacher.
nastavnik/nastavnica: teacher (often middle/high school).
profesor/profesorica: professor; commonly used for high-school and university teachers, and as a respectful form of address. Context matters and usage overlaps.

How do I say it if the teacher is female?

Use the feminine noun: Učiteljica trči s djecom poslije škole. The verb doesn’t change; only the noun’s gender does.

How does the verb agree if the subject is plural?

Use plural subject and verb:

Učitelji trče s djecom poslije škole. (Teachers run…) Conjugation of trčati (present): ja trčim, ti trčiš, on/ona trči, mi trčimo, vi trčite, oni/one trče.

Is there any ambiguity with s meaning “with” vs “from”?

Yes, but the case disambiguates:

s/sa
- instrumental = with (company/instrument): s djecom
s/sa
- genitive = from/off (a surface/place): sa stola (from the table), s krova (off the roof) So the case ending tells you the meaning.

How do I make the sentence negative?

Place ne before the verb:

Učitelj ne trči s djecom poslije škole. (The teacher does not run…)

How can I make “with the children” more specific or generic?

Generic/unspecified: s djecom (context decides if it’s “the” children)
Specific: s tom djecom (with those children), s njegovom djecom (with his children), s učenicima (with the pupils) if you mean his students.

Pronunciation tips for this sentence?

č in učitelj and trči is a hard “ch” (like English “ch” in church).
s djecom sounds like “sdye-tsohm” (the dj is a soft “dy” sound).
poslije is two syllables: “pos-lye”. You may hear casual speech variants, but standard spelling is poslije.