To, że dzieci śpiewają w chórze, naprawdę mnie cieszy.

In this sentence, To, że... is a very common Polish way to mean the fact that...

So:

• To, że dzieci śpiewają w chórze = The fact that the children sing in a choir

Here to does not mean a concrete this or it in the usual sense. It helps turn the whole clause że dzieci śpiewają w chórze into a subject-like idea: a fact, situation, or state of affairs.

A very literal breakdown would be:

• to = that / this fact
• że = that

Natural English usually does not translate both words separately, but as the fact that.

Polish normally uses a comma before że when it introduces a subordinate clause.

So in:

• To, że dzieci śpiewają w chórze, naprawdę mnie cieszy.

the clause że dzieci śpiewają w chórze is inserted after to, and the whole subject phrase is separated from the rest of the sentence with commas.

You can think of the structure like this:

• To, że dzieci śpiewają w chórze = subject
• naprawdę mnie cieszy = predicate/comment about that subject

So the commas help show where that subordinate clause begins and where the main part resumes.

Dzieci is the nominative plural form of dziecko (child).

Here it is the subject of śpiewają:

• dzieci śpiewają = the children sing / are singing

So dzieci is in the nominative, because it is the doer of the action inside that clause.

Important detail: dzieci is also used in some other cases, so the form itself can look familiar in different contexts. But here, because it is the subject of śpiewają, it is nominative plural.

Polish has no articles, so there is no direct equivalent of the or a/an.

That means dzieci can mean:

• children
• the children

Which meaning is intended depends on context.

In this sentence, English naturally uses the children, but Polish does not need a separate word for that.

Yes, śpiewają is the 3rd person plural present tense of śpiewać (to sing).

Because Polish present tense often covers both English meanings, it can mean:

• sing
• are singing

Which one fits best depends on context.

Here, since the sentence is about a general state of affairs, sing is usually the better English interpretation:

• That the children sing in a choir really makes me happy
• more naturally: The fact that the children sing in a choir really makes me happy

So this is probably not about what they are doing right this second, but about an ongoing fact.

The preposition w can mean in and often requires the locative case when it expresses location.

Here the meaning is in a choir, so Polish uses:

• w chórze

not:

• w chór

because chór must go into the locative after w in this sense.

Basic pattern:

• nominative: chór
• locative after w: w chórze

So w chórze literally means in a choir.

The verb cieszyć in this structure works like to please / to make someone happy.

So the grammar is:

• coś cieszy kogoś = something makes someone happy

Here:

• To, że dzieci śpiewają w chórze = the thing that causes happiness
• mnie = the person affected

So:

• mnie cieszy = makes me happy

Why not the other forms?

• ja is nominative, used for the subject, so it would be wrong here.
• mi is a dative form, but cieszyć takes an object like mnie / cię / go / ją / nas in this pattern.

Compare:

• To mnie cieszy. = That makes me happy.
• To cię cieszy. = That makes you happy.
• To nas cieszy. = That makes us happy.

Because the grammatical subject of cieszy is not just dzieci.

The subject of the main verb is the whole idea:

• To, że dzieci śpiewają w chórze

That whole clause functions as a single fact: the fact that the children sing in a choir.

So the main verb is singular:

• To ... cieszy

Inside the subordinate clause, however, dzieci is plural, so its own verb is plural:

• dzieci śpiewają

So there are really two layers:

1. dzieci śpiewają → plural verb, because children are plural
2. To, że dzieci śpiewają w chórze, cieszy → singular verb, because the whole clause is treated as one fact

Polish word order is quite flexible, and several versions are possible.

The given version:

• naprawdę mnie cieszy

is natural and emphasizes the speaker’s genuine feeling.

Other possible orders include:

• naprawdę cieszy mnie
• cieszy mnie naprawdę
• mnie naprawdę cieszy

But they may sound slightly different in emphasis or rhythm.

A very common neutral order in Polish is:

• To, że dzieci śpiewają w chórze, naprawdę mnie cieszy.

You will also often hear:

• To, że dzieci śpiewają w chórze, bardzo mnie cieszy.
• To, że dzieci śpiewają w chórze, cieszy mnie.

So yes, the order can change, but the original sentence is perfectly natural.

Naprawdę means really.

In this sentence it strengthens the feeling:

• cieszy mnie = makes me happy
• naprawdę mnie cieszy = really makes me happy

It suggests sincerity or genuine emotion. The speaker is not just stating a fact mechanically; they are emphasizing that this matters to them.

A near alternative is bardzo:

• bardzo mnie cieszy = makes me very happy

The difference is roughly:

• naprawdę = really, genuinely
• bardzo = very much

Sometimes both are possible, but they are not identical.

Yes, but the structure would change slightly.

You can say:

• Że dzieci śpiewają w chórze, naprawdę mnie cieszy.

This is understandable, but To, że... is often more natural and more clearly signals the fact that...

So:

• To, że dzieci śpiewają w chórze, ... = very common, clear, natural
• Że dzieci śpiewają w chórze, ... = possible, but a bit more marked or stylistically different

For many learners, To, że... is the safest pattern to remember.

They are related, but the grammar is different.

• cieszyć (kogoś) = to make someone happy
• cieszyć się = to be happy / to rejoice / to enjoy

In your sentence:

• To ... mnie cieszy = That makes me happy

If you used cieszyć się, you would need a different structure, for example:

• Cieszę się, że dzieci śpiewają w chórze. = I’m happy that the children sing in a choir.

So the meaning is similar, but the sentence is built differently:

• To mnie cieszy → something causes my happiness
• Cieszę się → I am happy

Both are very common in Polish.