Dopo l’interrogazione, ci mettiamo a ridere perché siamo tutte più tranquille.

Not usually. In a school context, interrogazione normally means an oral exam, oral test, or being questioned by the teacher.

So:

• Dopo l’interrogazione = After the oral exam / after being questioned

Even though the English word interrogation looks similar, in Italian interrogazione is very common in education and is not necessarily dramatic or police-related.

Because Italian usually uses the definite article more often than English.

Here:

• la interrogazione becomes l’interrogazione because the noun starts with a vowel.
• So dopo l’interrogazione literally means after the oral exam.

Italian often prefers the article where English might omit it or use a possessive/context instead.

Because the verb here is mettersi a + infinitive, which means to start / begin doing something.

The full verb is:

• mettersi = literally to put oneself
• mettersi a ridere = to start laughing

In the noi form:

• noi ci mettiamo a ridere = we start laughing

So ci is the reflexive pronoun meaning ourselves. It is part of the verb structure, not a separate idea like there.

It means to begin doing something, often with a sense of suddenly starting.

Examples:

• mettersi a ridere = to start laughing
• mettersi a piangere = to start crying
• mettersi a studiare = to start studying

So:

• ci mettiamo a ridere = we start laughing

It often sounds a bit more vivid than simply iniziare a.

Yes. Iniziamo a ridere is grammatically correct and means we begin to laugh.

But ci mettiamo a ridere is very idiomatic and often feels a little more natural for something that starts spontaneously.

A rough comparison:

• iniziamo a ridere = we begin to laugh
• ci mettiamo a ridere = we burst into laughter / we start laughing

The second one can feel more lively.

Because mettersi takes the preposition a before an infinitive in this pattern:

• mettersi a fare qualcosa

So you say:

• mettersi a ridere
• mettersi a parlare
• mettersi a lavorare

This is just the construction the verb uses, and it has to be learned as a set expression.

Because the subject is we, so the verb must be siamo:

• siamo = we are

Then:

• tutte = all (feminine plural)
• più tranquille = more relaxed / calmer (feminine plural)

So the whole part means:

• because we are all more relaxed

Because tutte is the feminine plural form of all.

Italian adjectives and similar words agree with the gender and number of the people they refer to. So if the group is all female, you get:

• tutte tranquille

If the group were all male, or mixed male and female, standard Italian would use:

• tutti tranquilli

So this sentence strongly suggests the speakers are female.

For the same reason: agreement.

Tranquillo/tranquilla changes form depending on who it describes:

• tranquillo = masculine singular
• tranquilla = feminine singular
• tranquilli = masculine plural
• tranquille = feminine plural

Since the subject is an all-female we, the adjective must be feminine plural:

• siamo tutte più tranquille

It means more relaxed / calmer, and the comparison is understood from the context.

Italian often leaves the second part of the comparison unstated when it is obvious. Here the idea is:

• more relaxed than before
• calmer now that the oral exam is over

So più does not need an explicit than before if the situation makes it clear.

In this sentence, siamo tutte più tranquille is the natural word order.

Here tutte works like all in English:

• we are all calmer
• siamo tutte più tranquille

That placement is very common and idiomatic. It comes before the adjective phrase it modifies.

Because Dopo l’interrogazione is an introductory time phrase:

• After the oral exam, ...

The comma helps separate that opening phrase from the main clause. In Italian, as in English, this comma is common and natural, especially in writing.

No. Here perché means because.

In Italian, perché can mean either:

• why
• because

You understand which one it is from the structure of the sentence.

Here it introduces a reason:

• ci mettiamo a ridere perché siamo tutte più tranquille
• we start laughing because we are all more relaxed

So it clearly means because.

Yes. Italian often leaves out subject pronouns when the verb ending already shows who the subject is.

Here:

• mettiamo already tells you the subject is we
• siamo also tells you the subject is we

So you do not need to say noi unless you want emphasis:

• Noi ci mettiamo a ridere... = We start laughing... with extra emphasis

It breaks down like this:

• Dopo l’interrogazione = after the oral exam
• ci mettiamo a ridere = we start laughing
• perché = because
• siamo tutte più tranquille = we are all more relaxed

So the pattern is:

time phrase + main clause + reason clause

This is a very natural Italian sentence structure.