Learn Hardcore Russian: Перед поездкой я не нервничаю, потому что заранее проверил паспорт и билеты. - Before the trip I don’t get nervous, because I checked my passport and tickets in advance.

The preposition перед (before / in front of) requires the instrumental case.
So поездка (trip) becomes поездкой (instrumental singular).
Pattern: перед + Instrumental → перед домом, перед встречей, перед поездкой.

Does Перед поездкой mean “before the trip” in time, or “in front of the trip” in space?

Here it’s time: before the trip.
Russian uses перед + instrumental for both space and time; the context tells you which:

перед домом = in front of the house (space)
перед поездкой = before the trip (time)

Why is я не нервничаю in the present tense if the sentence is about a specific trip?

Russian often uses the present tense to describe a habitual / typical reaction or what’s true “in general” around that situation:
Перед поездкой я не нервничаю ≈ “Before a trip, I don’t get nervous / I’m not nervous (in that pre-trip period).”

If you meant one specific trip right now, you could also say something like:

Перед этой поездкой я не нервничаю… (Before this trip, I’m not nervous…)

Why does the second verb switch to past: проверил?

Because the checking happened earlier and is already completed.
So Russian uses past + perfective aspect: проверил = “(I) checked (and it’s done).”
That completed action is presented as the reason you’re calm now.

What’s the difference between проверил and проверял here?

проверил (perfective) = checked once / achieved the result (confirmed everything).
проверял (imperfective) = was checking / checked repeatedly / focuses on the process.

In this sentence, the point is the result (everything is confirmed), so проверил is the natural choice.

Why is there no subject after потому что? Shouldn’t it repeat я?

Russian often drops repeated subjects when they’re obvious.
So …потому что заранее проверил… is understood as …потому что (я) заранее проверил….

You can include я for emphasis or contrast:

…потому что я заранее проверил… (because I checked in advance)

What does заранее add here? How is it different from раньше?

заранее means in advance / ahead of time—done beforehand with intention/planning.
раньше means earlier / formerly—just earlier in time, not necessarily “pre-planned.”

So заранее проверил = “I checked ahead of time (so I wouldn’t worry later).”

Why are паспорт и билеты in that form—what case are they?

They’re the direct objects of проверил, so they’re in the accusative.
For these nouns, accusative looks like the nominative:

паспорт (inanimate masculine) → accusative = паспорт
билеты (inanimate plural) → accusative = билеты

Why is there a comma before потому что?

Because потому что introduces a subordinate clause of reason (“because…”). In Russian, that subordinate clause is normally separated by a comma:

…, потому что …

Could I change the word order, e.g., put я first or move заранее?

Yes—Russian word order is flexible, and changes mainly affect emphasis:

Я перед поездкой не нервничаю… (emphasizes I)
…потому что проверил заранее паспорт и билеты. (emphasizes “in advance”)
The original order sounds neutral and natural.

How do I pronounce нервничаю and what does that ending mean?

нервничаю is 1st person singular present: “I get nervous / I’m nervous.”
Rough pronunciation: NYERV-nee-chah-yoo (stress typically on the first syllable: НЕ́рвничаю).
The ending -аю / -яю is common for many -ать verbs in the “I” form (e.g., читаю, работаю).