Learn Hardcore Russian: Учитель попросил нас сравнить два текста и найти различия. - The teacher asked us to compare two texts and find the differences.

Infinitive construction (used in your sentence)
- Pattern: попросить кого? сделать что?
- Example: Учитель попросил нас сравнить два текста.
- Literally: The teacher asked us (to) compare two texts.
  There is no чтобы here; the infinitive (сравнить, найти) directly expresses what you are asked to do.
Subordinate clause with чтобы
- Pattern: попросить (кого?), чтобы кто? сделал что?
- Example: Учитель попросил, чтобы мы сравнили два текста и нашли различия.
- Literally: The teacher asked that we compare two texts and find the differences.

Both are correct. The infinitive structure is a bit more direct and compact, and sounds very natural in neutral/colloquial Russian.

What is the grammatical pattern with попросил нас сравнить? How is this structured?

The key pattern is:

попросить кого? сделать что?

So in your sentence:

попросил – past tense, masculine, perfective, from попросить
кого? – нас (accusative case)
сделать что? – сравнить два текста и найти различия (two infinitive phrases joined by и)

You can think of нас сравнить not as a unit, but as:

попросил нас (asked us)
(он, учитель) попросил (нас) сравнить… – the understood subject of сравнить and найти is мы/нас.

So grammatically it is verb + object + infinitive.

Why is попросил (perfective) used, not просил?

Просить (imperfective) vs попросить (perfective):

просить focuses on the process / repeated action – “was asking / used to ask / would ask”.
попросить focuses on a single, completed request – “asked (once, and that’s it)”.

Here the teacher made one specific request: compare the texts and find the differences. The action of asking is seen as complete and whole, so Russian uses the perfective: попросил.

If you said:

Учитель просил нас сравнивать два текста.

it would sound more like “The teacher used to ask us / kept asking us to compare two texts” – a repeated or habitual situation.

Why are сравнить and найти in the perfective infinitive, not сравнивать and находить?

Again, aspect is about result vs process:

сравнить – perfective: to compare and finish the comparison, reach a result
найти – perfective: to find and actually locate the differences

Using imperfective here (сравнивать, находить) would focus on the ongoing process:

Учитель попросил нас сравнивать два текста и находить различия.

This would sound like a repeated or continuous task: He asked us to (routinely) compare two texts and (routinely) find differences – e.g., as a regular exercise in class.

In the given sentence, the teacher is assigning one task with a clear end result, so perfective infinitives сравнить and найти are natural.

What exactly is the difference between попросил and спросил?

Both can be translated as asked, but they are different types of “asking”:

спросить – to ask a question (request information)
- Учитель спросил нас, поняли ли мы задание.
- The teacher asked us if we understood the task.
попросить – to make a request (ask someone to do something or give something)
- Учитель попросил нас сравнить два текста.
- The teacher asked us to compare two texts.

So in this sentence the teacher is not asking for information; he is requesting an action, which is why Russian uses попросил, not спросил.

Why is it два текста and not две текста?

The choice between два and две depends on grammatical gender, not on what the word means.

два is used with masculine and neuter nouns.
две is used with feminine nouns.

Текст is a masculine noun, so you must say:

два текста

Examples for comparison:

два стола (two tables – masculine)
два окна (two windows – neuter)
две книги (two books – feminine)
две недели (two weeks – feminine)

Why is it различия in the plural, not a singular like различие or разницу?

In context, you usually expect several differences between two texts, so Russian naturally uses the plural:

найти различия – to find (the) differences

Nuances:

различие / различия is a bit more neutral or formal; it simply refers to differences.
разницу / разницы is slightly more colloquial, and often used when you mean “difference between A and B” in a more general everyday sense:
- Я не вижу разницы. – I don’t see a difference.

You could say:

найти разницу между двумя текстами – find the difference between the two texts (maybe suggesting there is one main difference)
найти различие между двумя текстами – find a difference (in the singular)

But if the idea is “find all the differences,” the plural различия is the most natural choice.

Could I say Учитель попросил, чтобы мы сравнили два текста… instead? What is the difference?

Yes, this is also correct:

Учитель попросил, чтобы мы сравнили два текста и нашли различия.

Differences in feel/structure:

Infinitive construction (original):
- Учитель попросил нас сравнить два текста и найти различия.
- More compact, very common in speech and writing.
- Grammatical pattern: попросить кого? сделать что?
Чтобы-clause construction:
- Учитель попросил, чтобы мы сравнили два текста и нашли различия.
- Slightly more formal or bookish, with a clearer separation of clauses.
- Pattern: попросить, чтобы кто? сделал что?

Meaning-wise, both express the same situation. The difference is mainly stylistic and syntactic, not semantic.

Why is the subject of сравнить and найти not expressed? Who is doing those actions?

In Russian, with verbs like просить / попросить, заставить, приказать, etc., followed by an infinitive, the doer of the infinitive is usually the same as the object of the main verb.

Pattern:

Учитель попросил нас сравнить…
– Teacher (subject) asked us (object) to compare (we will do the comparing).

Even though there is no explicit мы, it is understood that нас is the group who should сравнить and найти.

If you changed the structure:

Учитель попросил сравнить нас.

Now it means: He asked (someone) to compare us.
Here нас becomes the object of the infinitive (we are being compared), not the ones doing the comparing.

Can the word order be changed? For example: Учитель нас попросил сравнить два текста…?

Yes, Russian allows quite flexible word order, but it changes emphasis and sometimes clarity.

Some possible orders:

Учитель попросил нас сравнить два текста и найти различия.
– Neutral, standard, very natural.
Учитель нас попросил сравнить два текста и найти различия.
– Also correct; slightly more stress on нас (it was us he asked).
Нас учитель попросил сравнить два текста…
– Strong emphasis on нас: “It was us that the teacher asked (not someone else).”

But avoid separating нас too far from попросил in a way that might create ambiguity (for example around сравнить нас → “compare us”) unless context is crystal clear.

Why is there no comma before и найти различия?

In Russian, when you have two infinitives (or two verbs in the same form) joined by и and sharing the same subject and the same “governing” verb, you normally do not put a comma:

попросил нас сравнить два текста и найти различия

Both infinitives сравнить and найти:

depend on попросил
share the same understood subject (мы/нас)
are equal parts of the same request

So they form a simple compound predicate in the infinitive, and no comma is needed.

If the parts were more independent or had different subjects/structures, a comma could appear, but not in this basic case.

How is this sentence pronounced? Where are the stress accents?

Here is the sentence with stressed syllables marked in uppercase (for illustration):

УчИтель – u-CHI-tel’ (stress on И)
попросИл – pa-pro-SIL (stress on И)
нас – one syllable
сравнИть – srav-NIT’ (stress on И)
два – one syllable
тЕкста – TEK-sta (stress on Е)
и – one syllable
найтИ – nai-TI (stress on И)
разлИчия – ra-ZLI-chi-ya (stress on И)

Connected speech will sound roughly like:

учи́тель попроси́л нас сравни́ть два те́кста и найти́ разли́чия.

If the teacher is a woman, can we still use учитель, or must it be учительница?

Both are possible, but with different nuances:

Учитель – grammatically masculine; can refer to:
- a male teacher, or
- a female teacher in a formal / official / job title sense (e.g., in documents, announcements).
Учительница – explicitly female teacher, more common in everyday speech when you clearly want to mark the teacher as a woman.

In your sentence:

Учитель попросил нас…
– Most naturally understood as a male teacher, because both the noun and the past-tense verb (попросил) are in the masculine form.

If the teacher is definitely female and you want to show that, you would normally say:

Учительница попросила нас сравнить два текста и найти различия.

Here both учительница and попросила are clearly feminine.