2.03 Prepositional Singular

Location, topic, stable singular endings, and the restricted second locative

Why the prepositional comes first

It is the only core Russian case that never appears without a preposition, and its common singular formation is comparatively regular.

The preposition and intended relation work together: в шко́ле 'in/at school', на рабо́те 'at work', о кни́ге 'about a book'. A memorised ending alone cannot select the phrase.
No bare form: *Я ду́маю кни́ге is impossible for 'I am thinking about the book'. Use о кни́ге.

Most masculine nouns take -е; -й and -ь disappear before the ending.

Written музее contains two е letters because the stem is музей- and the prepositional ending is -е. Do not compress it to *музе.
Stress: The ending may be stressed or unstressed: на столе́, в го́роде, в словаре́, об учи́теле. Store stress with the phrase.

Most -о nouns replace -о with -е; many -е nouns have the same visible nominative and prepositional shape.

Case is not always visible on the noun alone. In мо́ре the preposition and construction identify the form: Э́то мо́ре is nominative; Мы на мо́ре is prepositional.
Pronunciation: Stressed -е is clear in окне́. Unstressed written е after a soft consonant is shorter and more [i]-like in connected speech.

03.03 Neuter formation
Nominative	Prepositional	Observation
окно́	в окне́	-о → -е
сло́во	в сло́ве	-о → -е
мо́ре	на мо́ре	same written shape; context marks case
по́ле	в по́ле	same written shape
ружьё	о ружье́	ё becomes е when unstressed

-а and ordinary -я nouns normally take -е; feminine -ь takes -и.

Spelling: The form кни́ге is written with -е; the seven-letter -ы/-и restriction does not change every case ending after г.
Common mistake: Do not group every word ending in the letters -ия with ordinary -я nouns. Росси́я and исто́рия belong to a special /ij/-stem pattern and take -ии.

These common-looking endings deserve a separate spelling rule in the prepositional singular.

Compare ста́тья - о статье́. The letters -ья do not make a -ия noun; ста́тья follows the ordinary soft -я pattern.
Reliable visual cue: If the nominative ends exactly in -ий, -ия, or -ие, expect written -ии in the prepositional singular.

в + prepositional locates an entity inside a place, institution, area, or state.

Location is a relation, not simply a verb of no movement. Мы рабо́таем в музе́е and Мы хо́дим в музе́е can both describe an activity located inside the museum. A goal uses accusative and is taught next.
Form before translation: English in, at, and sometimes on do not map one-to-one onto Russian в. Learn the Russian place phrase as a lexical unit.

на + prepositional covers surfaces, many events, workplaces, islands, and conventional place frames.

The choice between в and на is partly semantic and partly lexical: в теа́тре but на конце́рте; в о́фисе but на рабо́те. Store frequent nouns with their location preposition.
Pair learning: Record two goal/location pairs later: на рабо́ту / на рабо́те, в теа́тр / в теа́тре.

03.07 Location with на
Phrase	Category
на столе́	surface
на рабо́те	conventional workplace frame
на уро́ке	event/session
на ста́нции	conventional place
на о́строве	island

Topic phrases answer о ком? о чём? after verbs and nouns of speech, thought, memory, and information.

Common governors include говори́ть о, чита́ть о, ду́мать о, мечта́ть о, вспомина́ть о, and расска́з о. The preposition, not the English gloss alone, establishes the prepositional case.
Pronunciation: о/об is normally unstressed and joins the following word in one sound group: о кни́ге, об исто́рии.

03.08 Topic with о, об, and обо
Form	Environment	Example
о	usual form	о кни́ге; о бра́те
об	before many vowel-initial words	об исто́рии; об о́пере
обо	restricted, especially pronouns/fixed clusters	обо мне; обо всём

A dictionary-listed group uses a special stressed location form after в or на.

The masculine ending is normally stressed -у/-ю. A smaller feminine -ь group shifts stress to final -и. The form is restricted to location and is not freely generated for new nouns.
Analysis: Treat в лесу́ as a restricted second locative, not as proof that every masculine prepositional can take -у.

03.09 The restricted second locative
Topic / ordinary prep.	Location	Contrast
о ле́се	в лесу́	about the forest / in the forest
о по́рте	в порту́	about the port / in the port
о мо́сте	на мосту́	about the bridge / on the bridge
о шка́фе	в шкафу́	about the cupboard / in the cupboard
о кро́ви	в крови́	about blood / in the blood
о те́ни	в тени́	about shade / in the shade

Select the preposition and relation before forming the noun.

Assessment
Form a location phrase: го́род, шко́ла, окно́.
Form a topic phrase: музе́й, тетра́дь, исто́рия.
Form: в + Росси́я; в + зда́ние; о + и́мя.
Choose the standard location: в ле́се or в лесу́.
Contrast destination and location using шко́ла, previewing the next module.
Explain why на мо́ре can be prepositional although мо́ре looks unchanged.
Answers and explanations
в го́роде; в шко́ле; в окне́.
о музе́е; о тетра́ди; об исто́рии.
в Росси́и; в зда́нии; об и́мени.
в лесу́; the restricted second locative marks location.
в шко́лу 'to school' versus в шко́ле 'in/at school'.
The nominative and prepositional forms are syncretic; the preposition and location relation identify the case.
Ready signal: Continue when you form -е/-и correctly and treat в/на selection and second locatives as lexical as well as grammatical.