На кафедре мне сказали, что реферат нужно сдать в пятницу.

In Russian, кафедра here means a university department / chair, and this noun is commonly used with на rather than в.

So:

• на кафедре = at the department
• not usually в кафедре

This is just the standard Russian collocation, and learners usually need to memorize it as a set expression.

Also, кафедре is the prepositional case form of кафедра, used after на when talking about location.

In this sentence, кафедра does not mean a physical lectern or podium. It means a department in a university, especially an academic department responsible for a subject area.

So на кафедре мне сказали means something like:

• They told me at the department
• I was told at the department office
• The department told me

Depending on context, English may translate it a little differently.

Because сказать кому-то means to tell someone.

The person receiving the information goes in the dative case:

• мне = to me
• тебе = to you
• ему / ей = to him / her

So:

• мне сказали = they told me

You cannot say я сказали, because я is nominative and would be the subject, but here I am not the one doing the telling.

You also cannot say меня сказали, because меня is accusative/genitive and is not used with сказать for the person being told.

There is no specific subject stated. Russian often uses the 3rd person plural to mean they in a vague, indefinite sense:

• мне сказали = they told me
• meaning: someone told me, I was told

This is very common in Russian when the speaker either:

• does not know who exactly said it,
• does not want to name the person,
• or the exact person is not important.

So сказали is plural, but it does not necessarily mean multiple people literally spoke.

Что introduces a subordinate clause, like that in English.

So:

• Мне сказали, что... = I was told that...

The part after что gives the content of what was said:

• реферат нужно сдать в пятницу = the paper needs to be handed in on Friday

This is one of the most common uses of что in Russian.

Реферат is often translated as:

• report
• paper
• term paper
• essay

But none of these is always a perfect match.

In Russian academic contexts, реферат often means a written assignment based on reading and summarizing material on a topic. It is usually more formal than just a short homework paragraph, but not necessarily a major research thesis.

So the best translation depends on context. In many learner-friendly translations, paper or report works well.

Нужно means it is necessary, need to, or must, depending on context.

In this sentence:

• реферат нужно сдать = the paper needs to be handed in / it is necessary to hand in the paper

This is an impersonal construction. Russian does not need an explicit subject like English often does.

A very literal breakdown would be:

• нужно = necessary
• сдать = to hand in / submit
• реферат нужно сдать = the paper, it is necessary to submit

Natural English would be:

• The paper needs to be submitted
• The paper must be handed in

Because сдать is the perfective form, and here the sentence refers to a single completed action: handing in the paper.

• сдать = to hand in / submit, with focus on completion
• сдавать = to be handing in / to hand in regularly / process-oriented imperfective

Since the idea is that the paper must be submitted by a certain deadline, Russian normally uses the perfective infinitive:

• нужно сдать в пятницу

This suggests a one-time action that should be completed.

The verb сдать comes from дать with the prefix с-.

• дать = to give
• сдать = to hand over, to turn in, to submit, sometimes to сдавать an exam = to take/pass depending on context

In academic contexts, сдать реферат means:

• to hand in a paper
• to submit an assignment

So the prefix changes the meaning quite a bit.

This is a great question because English speakers often expect the object of the infinitive to be in the accusative.

Here, реферат is grammatically the thing that is to be submitted, and in this impersonal construction it often stays in a nominative-like role in the sentence structure:

• Реферат нужно сдать

You can think of it as:

• As for the paper, it is necessary to submit it

Russian impersonal sentences with нужно, надо, можно, etc. often do not match English sentence structure exactly.

That said, Russian word order and case patterns can vary in related constructions, but Реферат нужно сдать is completely normal and standard.

Yes, that version is also natural:

• Мне сказали, что нужно сдать реферат в пятницу

The meaning is basically the same.

The difference is mostly in information focus:

• что реферат нужно сдать в пятницу puts реферат earlier, making it feel a bit more like the topic.
• что нужно сдать реферат в пятницу puts the emphasis first on the necessity: it is necessary to hand in...

Russian word order is flexible, and small changes often affect emphasis more than core meaning.

Literally, в пятницу means on Friday.

In many real contexts, though, when talking about deadlines, English may translate it as:

• on Friday
• by Friday

depending on what the speaker means in context.

Russian в пятницу itself most directly points to Friday as the relevant day. If the speaker wanted to make by Friday especially clear, they might use other wording such as:

• до пятницы = by Friday / before Friday

So without extra context, в пятницу usually means on Friday.

Because in Russian, a subordinate clause introduced by что is separated by a comma.

So:

• Мне сказали, что...

This is a standard punctuation rule in Russian. It is much more consistent than in English, where that is often not preceded by a comma.

Сказали is the past tense plural of the perfective verb сказать.

• говорить = to speak / to say, imperfective
• сказать = to say / tell, perfective

Here, perfective is used because the speaker refers to a completed act of telling:

• They told me
• not They were telling me

So мне сказали means that the information was communicated as a completed event.

Yes. In many contexts, нужно and надо are very close in meaning.

So you could say:

• На кафедре мне сказали, что реферат надо сдать в пятницу.

This would sound natural too.

Very roughly:

• нужно can sound a little more neutral or formal
• надо can sound a little more conversational

But in everyday speech, the difference is often small.

Yes, that is a good natural translation.

Russian often uses active forms like мне сказали where English may prefer a passive translation:

• мне сказали = they told me / I was told

Likewise:

• реферат нужно сдать = the paper needs to be handed in / the paper had to be handed in

So a passive English translation can sound very natural even though the Russian structure is different.