When someone asks you perché? (why?), you can recycle the same word in your response because perché also means “because”! Yes, two in one! Let’s look at the following example, where Daniela is asking her students to justify using one article over another. Make sure to look at the context and listen to the inflection!
L'articolo è uno. Uno scontrino, perché?
The article is "uno." "Uno scontrino" (a receipt). Why?
Perché la parola inizia per s più consonante.
Because the word starts with "s" plus a consonant.
Captions 54-56, Corso di italiano con Daniela - l'articolo indeterminativoPlay Caption
So perché actually has two grammatical forms. One is as an adverb meaning “for what reason.” It’s used in forming a question:
Perché l’hai interrogato?
Why did you interrogate him?
The other grammatical form of perché is a “causal conjunction” meaning “because.” It’s used to introduce the cause when it follows the effect (which might be simply implied as in our first example above). If we use a full sentence to respond to the above question, it might go something like this:
L’ho interrogato perché non l’hai fatto tu!
I interrogated him because you didn’t do it!
In the above example, “I interrogated him” is the effect and “you didn’t do it” is the cause, so perché (because) goes in the middle: effect-perché-cause.
But here’s the catch. If you want to put the cause first, such as when you’re explaining yourself without being asked, or elaborating on your reasons, then things change in Italian. In English you could technically start your full sentence answer with the cause, using “because.”
Because you didn’t interrogate him, I did.
However, in Italian you cannot use perché in this case. The word to go to is siccome (because, as, given that, whereas, or since), used exclusively to introduce the cause when it precedes the effect: siccome-cause-effect. Siccome and perché have similar meanings but are not interchangeable within the structure of the sentence. This may seem complicated, but once you get the hang of it, it will become natural. Here’s an example in context, where Lara is explaining her actions to Luca Manara.
Ginevra deve essere iscritta nella lista degli indagati e deve essere interrogata,
Ginevra must be recorded on the list of suspects and has to be interrogated,
e siccome non lo fai tu lo faccio io, tutto qui.
and because you're not doing it, I'm doing it, that's all.
Captions 17-19, Il Commissario Manara - S1EP3 - Rapsodia in BluPlay Caption
In the above example you could replace “because” with “given that,” "as," “whereas,” or “since.” But you can’t replace siccome with perché!
As your Italian becomes more fluent, you’ll find siccome to be extremely handy when you’re telling stories and explaining things. There are other similar words to call on as well, but we’ll save them for another time.
To get a feel for perché in both of its two contrasting but related meanings, “why” and “because,” check out their occurrences in Yabla videos (and figure out which is which). Do a search with siccome to get acquainted with it, and hear it in context. Then, to really grasp the mechanism, ask yourself some questions, and answer them. Get used to using perché as both the question “why” and the answer “because.” Then, elaborate on your answers using siccome and perché according to how you structure your sentence. Don’t forget the accent on perché!
Here’s a head start:
Perché sei così nervoso?
-Perché... è una storia lunga. Siccome avevo dimenticato di caricare la sveglia ieri sera, stamattina mi sono alzata tardi. E siccome avevo un appuntamento alle nove, non avevo tempo per fare colazione. Farò colazione al bar, perché ora ho fame. Dopo mi sentirò meglio, perché avrò la pancia piena. Siccome la pancia sarà piena, mi sentirò molto meglio.
Why are you so tense?
-Because... it’s a long story. Since I had forgotten to set the alarm last night, this morning I got up late. And because I had an appointment at nine, I didn’t have time for breakfast. I’ll have breakfast at the coffee shop because now I’m hungry. Afterwards I’ll feel better, because my stomach will be full. Since my stomach will be full, I’ll feel better.
To enhance your skills, make sure you practice ad alta voce (out loud), too.
Perché? Perché sì!