Learn Hardcore Italian: A casa riscaldo la zuppa con cura per non farla bollire troppo. - At home I heat the soup carefully so it doesn’t boil too much.

a casa literally means “at home.” When casa is used after the preposition a to indicate location, Italian omits the definite article. You say a scuola, a letto, a tavola, etc., without la or il.

Why is riscaldo in the present tense instead of a past tense?

The present tense in Italian can express:

An action happening right now (“I’m heating the soup”).
A habitual action (“Whenever I’m at home, I heat the soup”).
Using riscaldo here could be either “I’m reheating the soup” or “when I get home, I reheate it (as usual).”

What’s the difference between riscaldare and scaldare?

Both mean “to heat,” but with a nuance:

scaldare = heat (something) from a cold state; can also mean “to scald” (burn with hot liquid).
riscaldare = heat again or keep warm (reheat).
Since the soup was already cooked and cooled, you use riscaldare.

What does con cura mean, and how is it used here?

con cura = “with care” or “carefully.” It’s a prepositional phrase functioning adverbially to describe how you heat the soup. You could also say riscaldo la zuppa accuratamente, but con cura is very common.

How does the construction per non farla bollire troppo work, and why is la attached to far?

per
- infinitive expresses purpose (“in order to…”).
non negates the infinitive that follows.
far is the causative verb (“to make/let [something] do something”).
la = direct object pronoun referring back to la zuppa.

Putting it together:

per non = “so as not to”
farla = “make it” (far + la)
bollire = “boil” (infinitive)
troppo = “too much”

So per non farla bollire troppo = “so as not to make it boil too much.”

Could you instead say non far bollire troppo la zuppa?

Yes. Both are grammatically correct and convey almost the same idea. Differences:

non farla bollire troppo uses a pronoun, is a bit more compact.
non far bollire troppo la zuppa repeats the noun, maybe clearer for beginners.

Why is bollire in the infinitive and not conjugated as bolle?

Because after the causative far you use the infinitive of the action verb. You don’t say farla bolle, but farla bollire. Whenever you have fare + another verb, the second one stays in the infinitive.

Are there other ways to express purpose in Italian besides per + infinitive?

Yes. A common alternative is affinché + subjunctive. For example:

Affinché la zuppa non bolla troppo, la riscaldo con cura.
That’s more formal and requires the subjunctive (non bolla rather than non bolli here if it were true subjunctive, it’d be non bolla is indicative; the true subjunctive would be non bolla, but typically you’d see non bolla replaced by non bolla only in fixed expressions). In practice, per
- infinitive is simpler and more everyday.