Бабушка разрезала рулет и дала каждому по кусочку, а ватрушку оставила к чаю.

Бабушка is the subject of the sentence, so it stays in the nominative case.

The other nouns are direct objects, but their forms depend on gender and animacy:

• рулет is masculine inanimate, so its accusative looks the same as the nominative:

  • nominative: рулет
  • accusative: рулет

• ватрушка is feminine, so its accusative singular changes:

  • nominative: ватрушка
  • accusative: ватрушку

So:

• Бабушка разрезала рулет = Grandma cut the roll
• ватрушку оставила = left the sweet bun / cheese pastry

Разрезала is the perfective form, meaning she cut it up / cut it open / finished cutting it.

Compare:

• резала = was cutting, cut repeatedly, or describes the process
• разрезала = cut through, completed the action

In this sentence, the speaker presents a sequence of completed actions:

1. she cut the roll,
2. she gave everyone a piece,
3. she left the ватрушка for tea.

That is why perfective verbs fit well here:

• разрезала
• дала
• оставила

In Russian, рулет can mean a rolled cake, Swiss roll, meat roll, or another rolled food, depending on context.

Since the sentence also mentions кусочки and serving food to people, the learner should understand рулет here as some kind of food that can be sliced and shared.

So разрезала рулет means something like:

• cut up the roll
• sliced the roulade
• cut the Swiss roll / cake roll

The exact English word depends on context.

Каждому is the dative singular form of каждый.

The verb дать means to give, and the person who receives something is normally in the dative case.

So:

• дала кому? = gave to whom?
• каждому = to each person / everyone individually

This structure is very common:

• дала брату книгу = gave her brother a book
• дала детям конфеты = gave the children candy
• дала каждому по кусочку = gave each person a little piece

The pattern каждому по ... is very common in Russian and means one each, a share each, or apiece.

So:

• дала каждому по кусочку = gave everyone a piece each

After по in this kind of distributive meaning, Russian often uses the dative:

• по кусочку
• по яблоку
• по книге

This construction emphasizes distribution from one whole to several people.

Compare:

• дала каждому кусочек = gave each person a piece
• дала каждому по кусочку = gave each one a piece each / one little piece apiece

The second version sounds especially natural in Russian.

Кусочек is a diminutive of кусок.

• кусок = a piece, chunk
• кусочек = a little piece, a small piece

Diminutives in Russian can show:

• small size
• affection
• friendliness
• a softer, more natural everyday tone

Here по кусочку sounds very natural when talking about food, especially in a warm домашний context.

А often links two actions while also showing a contrast or switch of focus.

Here the contrast is roughly:

• she cut the roll and shared it with everyone,
• but/as for the ватрушка, she kept it for tea.

So а works better than и because the sentence is not just listing one more action. It sets ватрушку apart from рулет.

A natural sense is:

• she gave out the roll, whereas the ватрушка she saved for tea

Оставить к чаю means to save something for tea or to keep something to be eaten with tea later.

This is a very common Russian idea. К чаю often means:

• for tea
• to have with tea
• as something sweet to serve when tea is drunk

It does not necessarily mean physically placing something next to tea. It means keeping it for that occasion.

Examples:

• К чаю купили торт = They bought a cake for tea
• Оставь печенье к чаю = Save the cookies for tea

Ватрушка is a traditional Russian pastry, usually a small round bun with an open center filled with творог (farmer cheese / curd cheese), though other fillings exist too.

In translation, people may say:

• cheese pastry
• sweet bun
• curd bun

But often it is best simply to learn ватрушка as a cultural food word.

Because the subject is бабушка, which is grammatically feminine.

In the past tense, Russian verbs agree with the subject in gender and number:

• masculine: разрезал
• feminine: разрезала
• neuter: разрезало
• plural: разрезали

So:

• Бабушка разрезала
• бабушка дала
• бабушка оставила

All of them are feminine singular because бабушка is feminine singular.

The word order is natural, but Russian word order is more flexible than English word order.

Дала каждому по кусочку is the most neutral and natural way to say it here.

Other orders are possible, but they change emphasis:

• дала каждому по кусочку = neutral
• каждому дала по кусочку = emphasizes each person
• по кусочку дала каждому = emphasizes the distributed pieces

In this sentence, the chosen order flows well after разрезала рулет and keeps the focus on what Grandma did next.

Yes. That is one of the main things the sentence does.

The perfective verbs show a clear chain of finished events:

• разрезала = cut it
• дала = gave it out
• оставила = saved/left it

So the sentence paints a complete little scene:

Grandma sliced the roll, handed everyone a piece, and saved the ватрушка for tea.

That completed, story-like feel is very typical of perfective verbs in Russian narrative.