A scuola, nella mensa, si serve riso con verdure ogni martedì.

In Italian a scuola (without article) expresses the general idea of “at school” (i.e. attending school activities).
– alla scuola (a + la scuola) would point to a specific building (“to/at the school”) rather than the general setting.
– in scuola is unidiomatic: you use in + article with concrete places (e.g. nella scuola = “inside the school building”), but to say “at school” in the general sense you always say a scuola.

Both mean “in the cafeteria,” but:
– in mensa (article dropped) is common in everyday speech when you talk about the meal service in general.
– nella mensa (in + la mensa) literally “in the cafeteria” with the article, slightly more specific or formal.
In our sentence the writer chose nella mensa to stress the exact location.

This is the impersonal/passive use of si:
– si serve riso = “rice is served” or “one serves rice.”
– There is no explicit subject (“they serve”), and the meal itself becomes the focus.
It’s very common on menus and announcements.

In the impersonal si construction the verb agrees with the noun that follows:
– Here the direct object is riso (masculine, singular), so the verb takes third-person singular: si serve.
– If you had only verdure (feminine plural), you would say si servono verdure.

After an impersonal/passive si you normally omit the definite or partitive article when stating what is served.
– si serve riso con verdure simply lists the dishes in general.
You could add partitives (si serve del riso, delle verdure), but it’s more wordy and less common.

Italian offers several ways to say “every Tuesday”:
– ogni martedì literally “each Tuesday,” very clear.
– il martedì also means “on Tuesdays” (habitual) but sounds a bit more formal.
– Dropping both and just saying martedì at the end can work colloquially, but it’s ambiguous (could be “this Tuesday” or “Tuesdays” depending on context).
Using ogni martedì removes all doubt.

Yes, Italian is flexible with adverbials:
– Nella mensa a scuola si serve…
– Si serve riso con verdure ogni martedì nella mensa a scuola.
Commas are optional and used for clarity or emphasis. In your sentence they bracket the location info, but you could write it without commas if it still reads smoothly.

The accent marks the stressed vowel in words that are oxytone (stress on the last syllable).
– martedì is pronounced mar-te-DÌ, so the grave accent tells you the stress and distinguishes it from “martedi” (which could be misread).