English uses one little word — that — for jobs Russian splits across three. "I know that he's here," "the book that I read," and "I want him to come" all hide different Russian words: что (the conjunction "that"), кото́рый (the relative pronoun "which/who/that"), and что́бы (purpose / wish). Because English collapses them, learners default to что everywhere — and что is wrong in two of the three cases. This page gives you a test for each. The mechanics of each construction live on relative clauses with кото́рый and что vs что́бы as subordinators.
The three jobs at a glance
| Word | Job | Signature English |
|---|---|---|
| что | conjunction "that" — reports a fact after speak/think verbs | "I know that…" |
| кото́рый | relative pronoun — modifies a noun, agrees + declines | "the book that I read" |
| что́бы | purpose / volition — goal, or a wish for someone | "in order to…", "I want him to…" |
The decision test
Run these in order.
| # | Ask yourself… | If yes → |
|---|---|---|
| 1 | Does it modify a noun ("the X that…")? Could you say "which/who" instead? | кото́рый |
| 2 | Is it a goal ("in order to") or a wish for someone to do something? | что́бы |
| 3 | Is it reporting a fact after know/say/think/see? | что |
что — the conjunction "that" (a reported fact)
After verbs of speaking, thinking, knowing, feeling, and perceiving, что introduces a clause stating a fact. Note the comma before it — Russian always puts one there. Unlike English, this что can never be dropped.
Я зна́ю, что он уже́ здесь.
I know (that) he's already here. — что reports a fact after зна́ть; the comma is obligatory.
Она́ сказа́ла, что опозда́ет на полчаса́.
She said she'd be half an hour late. — что after a speaking verb; this is reported speech.
There is also a separate что = "what" (the question word), which survives inside the frame то, что ("the thing that / what"):
Я не по́нял то, что ты сказа́л.
I didn't understand what you said. — то, что = 'the thing that / what'; here что means 'what', not the conjunction.
кото́рый — the relative pronoun (modifies a noun)
When the clause describes a noun — "the man who called," "the book that I read" — use кото́рый. It is the workhorse relative pronoun, and it does two things English that never does:
- It agrees in gender and number with the noun it refers to (челове́к, кото́рый…; кни́га, кото́рая…; де́ти, кото́рые…).
- It takes the case its own clause needs — subject, object, after a preposition, etc.
Челове́к, кото́рый звони́л, не оста́вил и́мени.
The man who called didn't leave a name. — кото́рый: masculine (челове́к), nominative (it's the subject of 'called').
Кни́га, кото́рую я чита́л, лежи́т на столе́.
The book that I read is on the table. — кото́рую: feminine (кни́га) + accusative (object of 'read').
Друзья́, с кото́рыми мы е́здили в Крым, — э́то они́.
The friends we went to Crimea with — that's them. — с кото́рыми: instrumental after с; plural agreeing with друзья́.
что́бы — purpose and wishes
что́бы marks a goal ("in order to") or a wish/demand that someone else act. Its form depends on whether the subjects match:
- Same subject → что́бы + infinitive: "I came in order to help" (I came, I help).
- Different subjects → что́бы + past-tense verb: "I want him to come" (I want, he comes).
Я пришёл, что́бы помо́чь.
I came (in order) to help. — same subject (I came, I help) → что́бы + infinitive.
Я хочу́, что́бы ты пришёл во́время.
I want you to come on time. — different subjects (I want, you come) → что́бы + past-form пришёл.
That second pattern is where English speakers slip: "I want that you come" feels like a что-clause, but a wish about someone else's action is что́бы, never что.
The distinguishing insight: fact vs goal, and "is there a noun?"
Two cuts decide everything:
- Is a noun being described? If yes, it is кото́рый, no matter what. ("the book that…", "the friends who…")
- Is the clause a stated fact, or a wanted/aimed-for action? A fact you report → что. A goal or a wish for someone to act → что́бы. The giveaway: что́бы pairs with хоте́ть, проси́ть, ну́жно, "in order to"; что pairs with знать, ду́мать, сказа́ть, ви́деть.
Я зна́ю, что он придёт. — Я хочу́, что́бы он пришёл.
I know (that) he'll come. — I want him to come. — same English 'that/to', but reporting a fact = что; wishing he act = что́бы (+ past).
Common Mistakes
❌ Кни́га, что я чита́л, на столе́ (standard written register).
Wrong for normal prose — to modify a noun use кото́рую. (Bare что as a relative exists only in colloquial/folk speech and won't decline.)
✅ Кни́га, кото́рую я чита́л, на столе́.
The book I read is on the table.
❌ Я хочу́, что ты придёшь.
Wrong — a wish for someone else to act takes что́бы + past-form, not что + future.
✅ Я хочу́, что́бы ты пришёл.
I want you to come.
❌ Я пришёл, что помо́чь.
Wrong — purpose ('in order to') is что́бы, and with the same subject it takes the infinitive.
✅ Я пришёл, что́бы помо́чь.
I came to help.
❌ Челове́к, что́бы звони́л, не оста́вил и́мени.
Wrong — modifying a noun is кото́рый; что́бы is for purpose/wishes, never a relative pronoun.
✅ Челове́к, кото́рый звони́л, не оста́вил и́мени.
The man who called didn't leave a name.
Key Takeaways
- что = conjunction "that" reporting a fact after speak/think/know verbs (Я зна́ю, что…); the comma is obligatory and it can't be dropped. Separately, то, что = "the thing that / what."
- кото́рый = relative pronoun modifying a noun; it agrees in gender/number with that noun and declines for its own clause's case (кни́га, кото́рую я чита́л).
- что́бы = purpose or a wish for someone to act: same subject → + infinitive (что́бы помо́чь); different subjects → + past form (что́бы ты пришёл).
- The two cuts: noun being described → кото́рый; otherwise, fact → что, goal/wish → что́бы.
- English "that" maps to all three — never default to что.
Now practice Russian
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Russian→Related Topics
- Relative Clauses with КоторыйB1 — Кото́рый ('who/which/that') is the workhorse relative pronoun of Russian. It agrees in GENDER and NUMBER with its antecedent — the noun it points back to — but takes its CASE from its own role inside the relative clause. A comma before кото́рый is obligatory. This page teaches the two-question method that gets the form right every time and shows кото́рый across all six cases.
- Subordinating: Что and ЧтобыA2 — Что and чтобы look alike but do opposite jobs. Что (that) reports a fact after verbs of speaking, thinking, and knowing — and, unlike English 'that', it can never be dropped. Чтобы (in order to / that) introduces a goal or a wish, taking an infinitive when the subject stays the same and the past tense when it changes. This page draws the factual/volitional line and nails the obligatory comma.
- Говорить / Сказать (to speak / say)A1 — Complete conjugation-and-usage reference for the suppletive pair говори́ть (imperfective, 'speak/talk/say generally') and сказа́ть (perfective, 'say/tell — a single utterance'). Full paradigms — говорю́/говори́шь/говоря́т, скажу́/ска́жешь/ска́жут with the з→ж mutation — the meaning split говори́л vs сказа́л, and the contrast with разгова́ривать.
- Этот vs Тот; Это (pointing) vs Этот (modifying)B1 — Two demonstrative decisions in one place: э́тот ('this, near') vs тот ('that, far / the other / the aforementioned'), and the frozen pointer э́то ('this/that is…', invariable) vs the agreeing demonstrative э́тот/э́та/э́то that modifies a noun. A replacement test settles each case.