Learn Hardcore Ukrainian: Вони пишуть одне одному повідомлення під час перерви. - They write messages to each other during the break.

It means “to each other.” It’s the standard reciprocal construction in Ukrainian: literally “one (to) one,” used to express mutual action between the participants.

Why is it “одне одному” (dative) and not something with a preposition like “до” or “для”?

Because Ukrainian uses the dative case for recipients with the verb писати (to write). The pattern is:

писати (що?) комусь = “to write (what?) to someone” So “to each other” becomes dative: одне/один/одна — одному/одній. No preposition is needed.

Should it be “один одному” instead of “одне одному” when talking about people?

Both are understood. In everyday usage about people, один одному is the most common and stylistically neutral. Одне одному is also used (some speakers prefer it for gender‑neutrality, and it’s regular with neuter plural nouns), but if you want the safest, most typical choice for people, use один одному. For an all‑female group: одна одній.

What case are the forms in “одне одному,” and how do they change with different verbs?

In this sentence, it’s dative: одному = “to one.”
With verbs that take the accusative (e.g., “see”), you’d use the accusative: вони бачать один одного = “they see each other.”
With verbs that take the dative (e.g., “help,” “write”): вони допомагають/пишуть один одному = “they help/write to each other.”

Is “повідомлення” singular or plural here?

It’s ambiguous in form. Повідомлення (neuter) has the same form in nominative/accusative singular and plural. Context usually tells you:

Likely plural here (“messages”), since they’re writing to each other. To force a meaning:
Singular: одне повідомлення, лише одне повідомлення
Plural: кілька/багато повідомлень (note the genitive plural: повідомлень)

Why doesn’t “повідомлення” change in the accusative?

For inanimate neuter nouns, the accusative form equals the nominative. So:

Nom. sg = Acc. sg: повідомлення
Nom. pl = Acc. pl: повідомлення That’s why you see the same shape.

Why is there no article (“a/the”) before “повідомлення”?

Ukrainian has no articles. Definiteness/indefiniteness is inferred from context or expressed with other words (e.g., це “this,” одне “one,” ці “these,” etc.).

What exactly does “під час перерви” mean, and which case is “перерви”?

Під час is a fixed complex preposition meaning “during” and it governs the genitive. Перерви is genitive singular of перерва (“break, recess”). So: “during the break.”
Common alternative: на перерві (“at break, during the break”); it’s very natural in school contexts. Під час перерви emphasizes the time span a bit more formally/literally (“during the time of the break”).

Can I change the word order?

Yes—Ukrainian word order is flexible. All of these are fine, with slight shifts in emphasis:

Під час перерви вони пишуть одне одному повідомлення. (fronted time)
Вони пишуть повідомлення одне одному під час перерви. (recipient later)
Вони одне одному пишуть повідомлення під час перерви. (recipient emphasized) Meaning stays the same.

What’s the aspect/tense nuance of “пишуть”?

Пишуть is present tense, imperfective:

It can mean “are writing (right now)” or “write (habitually).” Perfective counterpart: написати:
Future (completed): вони напишуть (“they will write [and finish]”)
Past (completed): вони написали (“they wrote [and finished]”) Imperfective future (ongoing/repeated): вони писатимуть (“they will be writing / will write [repeatedly]”)

Could I place “одне одному” after “повідомлення”?

Yes: Вони пишуть повідомлення одне одному під час перерви. Both placements are natural. Putting the recipient earlier can make it feel a bit more topical (“to each other, they write messages…”).

How would I say this more succinctly as “They are texting each other during the break”?

Use the reciprocal reflexive verb переписуватися (“to be text‑messaging / exchanging messages”):

Вони переписуються під час перерви. No одне одному is needed with the reflexive reciprocal.

Any quick pronunciation tips for the sentence?

Вони пишуть: “вони” sounds like vo-NY; пишуть like PY-shut; the final “ть” is written but often not fully released in casual speech.
одне одному: pronounce adjacent vowels separately: od-NE od-NO-mu.
під час: “ч” is like English “ch.”
перерви: stress typically on the second syllable: pe-RER-vy. Overall: Vony PY-shut od-NE od-NO-mu povy-DOM-len-nia pid chas pe-RER-vy.

Are there synonyms for “повідомлення” I might hear?

лист = a letter (paper or long email)
СМС / есемеска = an SMS text
повідомлення в чаті/месенджері = a chat/message app message Повідомлення is the safest general word for “message/notification.”

Do I need any commas in this sentence?

No. It’s a simple declarative sentence with no subordinate clauses, so no commas are required.