Why prepositional comes first
Its adjective endings are regular and its location meanings create a clean contrast for later accusative destinations.
- The prepositional case occurs only with prepositions. The adjective copies the case, number, and gender of the head noun.
- Control point: First choose the prepositional relation for the noun phrase; only then choose adjective agreement.
3.03 · Why prepositional comes first · table 1
| Relation | Frame | Example |
| location | в + prep. | в но́вом до́ме |
|---|
| setting | на + prep. | на но́вой рабо́те |
|---|
| topic | о/об + prep. | об интере́сной кни́ге |
|---|
| head control | whole phrase | но́вом agrees with до́ме |
|---|
Masculine and neuter hard -ом
Hard-family masculine and neuter adjectives share prepositional singular -ом.
- Gender remains a property of the head noun, even though the adjective ending is syncretic across masculine and neuter.
- Control point: The adjective ending does not predict the noun ending: до́ме, окне́, го́роде, зда́нии follow noun rules.
3.03 · Masculine and neuter hard -ом · table 1
| Nominative | Prepositional | Phrase |
| но́вый дом | но́вом | в но́вом до́ме |
|---|
| но́вое окно́ | но́вом | в но́вом окне́ |
|---|
| ста́рый го́род | ста́ром | в ста́ром го́роде |
|---|
| кра́сное зда́ние | кра́сном | о кра́сном зда́нии |
|---|
True soft and sibilant -ем
Genuinely soft and many sibilant-family adjectives use masculine/neuter prepositional -ем.
- Keep the diagnostic family active. The same visible ending may follow different stem histories.
- Control point: Stress can change the written vowel after a sibilant: хоро́шем but большо́м.
- Retrieval checkpoint: Pause and reconstruct the diagnostic forms from the last three lessons without looking, then check what you missed.
3.03 · True soft and sibilant -ем · table 1
| Nominative | Prepositional | Phrase |
| си́ний | си́нем | о си́нем мо́ре |
|---|
| ле́тний | ле́тнем | в ле́тнем ла́гере |
|---|
| хоро́ший | хоро́шем | о хоро́шем враче́ |
|---|
| большо́й | большо́м | в большо́м го́роде |
|---|
Feminine -ой and -ей
Feminine prepositional singular uses -ой or -ей across location and topic constructions.
- The noun has its own ending; both words must be formed. Genuinely soft and sibilant families commonly show -ей.
- Control point: Feminine -ой is highly syncretic: the same form will later appear in genitive, dative, and instrumental contexts.
3.03 · Feminine -ой and -ей · table 1
| Nominative | Prepositional | Phrase |
| но́вая кни́га | но́вой | о но́вой кни́ге |
|---|
| си́няя ру́башка | си́ней | в си́ней ру́башке |
|---|
| ру́сская шко́ла | ру́сской | в ру́сской шко́ле |
|---|
| хоро́шая иде́я | хоро́шей | о хоро́шей иде́е |
|---|
| больша́я ко́мната | большо́й | в большо́й ко́мнате |
|---|
Diagnostic families in one table
A compact comparison prevents false hard/soft generalisations.
- Form the adjective from its stored family, then form the noun independently.
- Control point: Store four diagnostics when necessary: masculine nominative, feminine nominative, genitive masculine/neuter, and a plural oblique form.
3.03 · Diagnostic families in one table · table 1
| Family | Masc./neut. prep. | Fem. prep. |
| но́вый | но́вом | но́вой |
|---|
| си́ний | си́нем | си́ней |
|---|
| ру́сский | ру́сском | ру́сской |
|---|
| хоро́ший | хоро́шем | хоро́шей |
|---|
| большо́й | большо́м | большо́й |
|---|
Location with в
в + prepositional places an activity, state, or object inside a setting.
- The verb does not need to be motionless. What matters is whether the phrase locates the event rather than naming its endpoint.
- Control point: Do not reduce the contrast to 'movement versus no movement'. Endpoint meaning, not the presence of motion, selects accusative.
- Retrieval checkpoint: Pause and reconstruct the diagnostic forms from the last three lessons without looking, then check what you missed.
3.03 · Location with в · table 1
| Example | Located element | Meaning |
| Мы живём в но́вом до́ме. | living | inside the house |
|---|
| Она́ рабо́тает в ру́сской шко́ле. | working | at/in the school |
|---|
| Де́ти бе́гают в большо́м па́рке. | running | activity located in park |
|---|
| Кни́га лежи́т в си́ней су́мке. | book | inside bag |
|---|
Location and setting with на
на + prepositional covers surfaces and many conventional activity, event, and institutional frames.
- The choice between в and на is partly lexical. Learn common place frames with the noun and adjective together.
- Control point: Translate the whole place relation, not an isolated English preposition.
3.03 · Location and setting with на · table 1
| Frame | Example | Category |
| на столе́ | на большо́м столе́ | surface |
|---|
| на рабо́те | на но́вой рабо́те | activity/institution |
|---|
| на уро́ке | на интере́сном уро́ке | event |
|---|
| на стадио́не | на но́вом стадио́не | conventional place frame |
|---|
Topic with о and об
о/об + prepositional marks the topic of speech, thought, writing, or information.
- Use об before many vowel-initial sound groups to avoid hiatus. The case remains prepositional throughout the phrase.
- Control point: Choose о/об for pronunciation, then form the same prepositional agreement pattern.
3.03 · Topic with о and об · table 1
| Frame | Example | Topic |
| о | о но́вом прое́кте | a new project |
|---|
| о | о ру́сской литерату́ре | Russian literature |
|---|
| об | об интере́сной исто́рии | an interesting story |
|---|
| об | об о́пытном учи́теле | an experienced teacher |
|---|
Second-locative nouns keep ordinary adjectives
A restricted noun ending -у/-ю does not create a special adjective locative ending.
- The adjective uses the ordinary prepositional form while a small lexical set of masculine nouns may use a stressed second locative for location.
- Control point: The special form belongs to the noun. The agreeing adjective remains prepositional singular.
- Retrieval checkpoint: Pause and reconstruct the diagnostic forms from the last three lessons without looking, then check what you missed.
3.03 · Second-locative nouns keep ordinary adjectives · table 1
| Location | Topic/ordinary prep. | Contrast |
| в густо́м лесу́ | о густо́м ле́се | location vs. topic |
|---|
| на но́вом мосту́ | о но́вом мо́сте | location vs. topic |
|---|
| в да́льнем углу́ | о да́льнем угле́ | location vs. ordinary form |
|---|
| в но́вом шкафу́ | о но́вом шка́фе | location vs. topic |
|---|
Prepositional singular assessment
Select the preposition and relation, then form both adjective and noun.