Контролёр в трамвае проверила билет и улыбнулась ребёнку.

Because контролёр is one of those Russian nouns that can refer to a man or a woman, even though its dictionary form looks grammatically masculine.

In this sentence, the past-tense verb проверила shows that the controller/inspector was female:

• проверил = he checked
• проверила = she checked

So контролёр here means a female ticket inspector/controller.

Russian often does this with job titles:

• врач пришёл = the doctor (male) came
• врач пришла = the doctor (female) came

The same pattern is happening here.

Not in the usual English sense of someone controlling a machine or system.

In this context, контролёр means a person who checks tickets on public transport — essentially a ticket inspector.

So:

• Контролёр в трамвае = The ticket inspector on the tram

That is the most natural interpretation here.

Because в + prepositional case is used here to mean in/on the tram, meaning location.

• трамвай = tram
• prepositional singular: в трамвае = in/on the tram

This tells you where the action happened.

A learner may notice that Russian can use both в and на with transport in different situations:

• в трамвае = inside the tram / on the tram
• ехать на трамвае = to go by tram

So here, since the inspector is physically there and doing something inside the vehicle, в трамвае is completely natural.

It is in the accusative — it just happens to look the same as the nominative.

The verb проверить takes a direct object, so билет is in the accusative case.

For inanimate masculine singular nouns, nominative and accusative are usually identical:

• nominative: билет
• accusative: билет

Compare:

• Я вижу стол. = I see the table.
• Я проверила билет. = I checked the ticket.

If the noun were animate, the accusative would often look different.

Because the verb улыбнуться takes the dative case, not a direct object.

In Russian, you smile to someone, not exactly smile someone.

So:

• ребёнок = child
• dative singular: ребёнку = to the child

That gives:

• улыбнулась ребёнку = smiled at the child

This is a very common pattern:

• помочь другу = help a friend
• позвонить маме = call mom
• улыбнуться ребёнку = smile at the child

Улыбнулась means smiled.

It comes from the verb улыбнуться, which is a reflexive verb. The -ся / -сь ending is the reflexive marker.

Here:

• infinitive: улыбнуться
• past feminine: улыбнулась

The -сь form appears after a vowel; -ся is the same marker in a slightly different form.

You do not need to translate the reflexive part literally as herself here. In this verb, it is just part of the normal dictionary form:

• улыбаться / улыбнуться = to smile

So улыбнулась ребёнку simply means she smiled at the child.

Because the sentence narrates completed actions in the past.

The forms are:

• проверила = checked
• улыбнулась = smiled

Both are feminine singular past forms, agreeing with the female контролёр.

Russian past tense is often easy to spot:

• masculine: usually -л
• feminine: usually -ла
• neuter: usually -ло
• plural: usually -ли

So:

• проверил / проверила / проверило / проверили
• улыбнулся / улыбнулась / улыбнулось / улыбнулись

Both verbs are perfective:

• проверить → проверила
• улыбнуться → улыбнулась

Perfective aspect presents each action as a whole, as a completed event:

• she checked the ticket
• she smiled at the child

That fits a short narrative sequence very well.

If imperfective verbs were used, the meaning would shift:

• проверяла could suggest she was in the process of checking, or checked habitually/repeatedly
• улыбалась could suggest she was smiling for some time

Here the sentence sounds like a simple completed event, so perfective is natural.

Because Russian has no articles.

So контролёр, билет, and ребёнку can mean:

• a controller / the controller
• a ticket / the ticket
• to a child / to the child

English has to choose, but Russian usually leaves this to context.

In this sentence, English would most naturally say something like:

• The ticket inspector on the tram checked the ticket and smiled at the child.

But Russian does not need separate words for the.

The word order is fairly neutral and natural for a short narrative sentence.

• Контролёр в трамвае sets up the person and location
• проверила билет gives the first action
• и улыбнулась ребёнку gives the second action

Russian word order is more flexible than English because case endings show grammatical roles. So other orders are possible, for example:

• В трамвае контролёр проверила билет и улыбнулась ребёнку.

That would put a bit more emphasis on the setting: On the tram, the inspector checked the ticket and smiled at the child.

But the original order is completely normal.

И simply means and.

It links two actions done by the same person:

• проверила билет = checked the ticket
• улыбнулась ребёнку = smiled at the child

Since the subject is the same, Russian does not repeat it:

• Контролёр ... проверила билет и улыбнулась ребёнку.

This is just like English:

• The inspector checked the ticket and smiled at the child.

It is in the prepositional case.

The base noun is:

• трамвай = tram

After в meaning location, Russian uses the prepositional:

• в трамвае = in/on the tram

So the cases in the sentence are:

• контролёр = nominative subject
• в трамвае = prepositional after в
• билет = accusative direct object
• ребёнку = dative after улыбнуться

This sentence is actually a nice compact example of several common Russian cases working together.