Пластилин лежит рядом с наклейками, потому что дети ещё не убрали его после урока.

In Russian, the verb to be in the present tense is usually omitted.

So instead of saying something like The modeling clay is lying..., Russian simply says:

Пластилин лежит...

Also, лежит is not just a neutral is. It specifically means is lying or is located in a lying position. Russian often chooses a position verb where English might just say is.

Russian often distinguishes between different kinds of being somewhere:

• лежать = to lie
• стоять = to stand
• сидеть = to sit
• находиться = to be located

Пластилин is treated as something that typically lies rather than stands, so лежит sounds natural.

For example:

• Книга лежит на столе = The book is lying on the table
• Бутылка стоит на столе = The bottle is standing on the table

So Пластилин лежит рядом с наклейками means the plasticine/modeling clay is there in a lying/resting position.

The expression рядом с means next to, beside, or near.

It works as a fixed combination:

• рядом с чем? = next to what?

So:

• рядом с наклейками = next to the stickers

You should learn рядом с as a unit, because рядом by itself often needs с + instrumental to name the thing that is nearby.

Because after с in the expression рядом с, Russian uses the instrumental case.

The dictionary form is:

• наклейки = stickers

Instrumental plural becomes:

• наклейками

So:

• рядом с наклейками = next to the stickers

This is one of the most common patterns to memorize:

• с другом = with a friend
• с книгой = with a book
• рядом с домом = next to the house
• рядом с наклейками = next to the stickers

Потому что means because.

It introduces the reason:

• ..., потому что дети ещё не убрали его...
• ..., because the children haven’t put it away yet...

Russian can sometimes express cause in other ways, but потому что is the standard, straightforward way to say because.

Using only что here would be wrong, because что usually means that or what, not because.

Here ещё means yet.

So:

• ещё не убрали = have not put away yet

This is a very common pattern:

• ещё не знаю = I don’t know yet
• ещё не пришёл = he hasn’t arrived yet
• ещё не убрали = they haven’t put it away yet

Be careful: ещё can also mean still, more, or another, depending on context. In this sentence, with negation, it clearly means yet.

This is an aspect question.

• убрать / убрали = perfective, focuses on completion
• убирать / убирали = imperfective, focuses on process, repetition, or general activity

Here the sentence means the children have not completed the action of putting it away. That is why Russian uses the perfective:

• не убрали = did not put away / have not put away

If you said не убирали, it would sound more like they were not putting it away, they did not do the putting-away, or it could stress the process rather than the missing result.

Since the important point is that the plasticine is still there because the action was not completed, не убрали is the natural choice.

Because the subject is дети = children, which is plural.

Russian past tense agrees in number, and in the singular also in gender:

• он убрал = he put away
• она убрала = she put away
• оно убрало = it put away
• они убрали = they put away

Since дети is plural, the verb must be убрали.

Его is the pronoun him/it in this sentence, and here it means it.

It refers back to пластилин.

So:

• дети ещё не убрали его = the children haven’t put it away yet

Because пластилин is masculine singular, the pronoun used is его.

A useful note:

• его can mean him or it depending on context
• here it clearly means it, because the referent is пластилин

You could sometimes omit an object in Russian if it is obvious from context, but here его makes the sentence clearer and more natural.

Without его, the sentence would sound less complete because убрать usually expects an object when you mean put something away.

So:

• не убрали его = haven’t put it away
• не убрали by itself could sound incomplete unless the object is already extremely obvious from context

Including его helps explicitly connect the second clause back to пластилин.

The preposition после takes the genitive case.

The dictionary form is:

• урок = lesson

Genitive singular:

• урока

So:

• после урока = after the lesson

This is a standard pattern:

• после работы = after work
• после школы = after school
• после фильма = after the film
• после урока = after the lesson

Yes. Russian word order is more flexible than English, although the original sentence is neutral and natural.

For example, you could also say:

• Пластилин лежит рядом с наклейками, потому что его дети ещё не убрали после урока.
• Потому что дети ещё не убрали его после урока, пластилин лежит рядом с наклейками.

These versions are grammatically possible, but they may shift emphasis or sound less neutral.

The original order is good because it:

1. states the situation first
2. gives the reason after that

That is a very common structure in Russian.

Пластилин is singular.

Russian has no articles like a, an, or the. So пластилин can mean:

• plasticine
• the plasticine
• some plasticine

The exact meaning depends on context.

In this sentence, the context tells us that it is a specific thing already being talked about, so in English it would often be translated as the plasticine or simply plasticine/modeling clay.

Russian does not have articles, so наклейками by itself does not explicitly tell you whether the meaning is stickers, the stickers, or sometimes even some stickers.

The form наклейками only tells you:

• the noun is plural
• it is in the instrumental case

So the difference between stickers and the stickers comes from context, not from an article.

In this sentence, English would often naturally use the stickers if they are specific stickers known in the situation.