Learn Hardcore Russian: Ночью фонарик помог нам найти дорогу, а компас показал правильное направление. - At night the flashlight helped us find the way, and the compass showed the right direction.

So Ночью фонарик помог нам… literally feels like “By night / At night, the flashlight helped us…”.
Using nominative Ночь фонарик помог нам… would be ungrammatical here.

Why isn’t there a preposition, like в, before ночью?

With time expressions, Russian often does not need a preposition. The instrumental case itself carries the meaning “at that time”.

Compare:

Ночью = at night
Летом = in summer
Зимой = in winter

You can say в ночь only in some special, more literary contexts (e.g. в ночь на субботу – on the night before Saturday), but for the general “at night” meaning, the normal form is just Ночью without a preposition.

What exactly is the difference between фонарик and фонарь?

Both come from the same root, but:

фонарь usually means a lamp, often a streetlamp or any general lamp/light.
фонарик is a diminutive form, literally “little lamp,” and in modern usage it very often means a flashlight / torch (the handheld device).

In contexts like найти дорогу ночью, фонарик is naturally understood as a flashlight you carry, not a big streetlight.

Why is it помог нам, not помог нас?

The verb помочь / помогать (to help) requires the dative case for the person who is helped:

Помочь кому? — help whom? (in Russian: to whom?) → мне, тебе, нам, им.

So:

фонарик помог нам — the flashlight helped us (dative).
Нам is dative; нас would be accusative and would be incorrect here.

What is the nuance of помог (perfective) instead of помогал (imperfective)?

помог is perfective past: a completed, one-time result — “(it) helped us (and we found the road).”
помогал is imperfective past: a process or repeated action — “(it) was helping / used to help.”

In this sentence, the focus is on a single successful event: at night, in that situation, the flashlight did the job once and for all, so Russian uses помог, not помогал.

Why is найти (to find) in the infinitive after помог?

In Russian, помочь / помогать is usually followed by an infinitive that tells us what action someone was helped to do:

Он помог мне сделать домашнее задание. – He helped me do my homework.
Она помогла нам купить билеты. – She helped us buy the tickets.

So here:

фонарик помог нам найти дорогу
= “the flashlight helped us find the road.”

This помочь + dative + infinitive pattern is very common.

Why is it дорогу, not дорога?

Дорога (road) is a feminine noun:

nominative: дорога
accusative: дорогу

In найти что? (find what?), “what” is a direct object and must be in the accusative case:

найти дорогу – to find the road
увидеть машину – to see a car
купить книгу – to buy a book

So дорогу is the correct accusative form.

What is the role of а between the two clauses, and how is it different from и?

Both а and и can translate as “and”, but:

и simply adds, links items/actions with no contrast:
- Он купил хлеб и молоко. – He bought bread and milk.
а often shows a contrast, shift, or mild opposition between parts:
- Я люблю чай, а он — кофе. – I like tea, and (but) he likes coffee.

In this sentence:

…фонарик помог нам найти дорогу, а компас показал правильное направление.

А subtly contrasts the different roles:

flashlight → helped find the road
compass → showed the direction

You could use и here too, but а feels slightly more natural because the devices do different helpful things.

Why are the verbs помог and показал masculine singular, even though нам means “us”?

In Russian, the verb in the past tense agrees with the subject, not the object.

Subjects here are:

фонарик – masculine singular
компас – masculine singular

Past masculine singular forms:

помог (from помочь)
показал (from показать)

Нам is just the indirect object (dative “to us”), so it does not affect the verb’s gender or number. That’s why both verbs are masculine singular.

Why is it показал правильное направление and not показал на правильное направление?

The verb показать has two common patterns:

показать что? – show what? (direct object, no preposition)
- Он показал мне дорогу. – He showed me the road.
- Компас показал правильное направление. – The compass showed the right direction.
показывать / показать на что? – point at something
- Он показал на карту. – He pointed at the map.
  Here на + accusative means “at / towards”.

In your sentence, the compass “showed the direction itself”, not “pointed at” something, so на is not used. Правильное направление is the direct object of показал.

Why is it правильное направление, and how does the agreement work?

Направление (direction) is a neuter noun:

nominative: направление
accusative: направление (same form in neuter)

The adjective правильный must agree with the noun in gender, number, and case:

masculine: правильный путь – the right way
feminine: правильная дорога – the right road
neuter: правильное направление – the right direction
plural: правильные решения – the right decisions

Since направление is neuter singular in the accusative, the adjective becomes правильное (neuter singular accusative), which in neuter equals the nominative form.

Could the word order be different, like Ночью нам фонарик помог найти дорогу?

Yes, Russian word order is relatively flexible, and your version is grammatically correct:

Ночью фонарик помог нам найти дорогу.
Ночью нам фонарик помог найти дорогу.

Both are possible. The differences are mainly in rhythm and emphasis:

фонарик помог нам (original) is fairly neutral.
нам фонарик помог can slightly emphasize нам (“it was us that the flashlight helped”) or фонарик (“it was the flashlight that helped us”), depending on intonation.

In everyday speech, the original order is very natural, but word-order shuffles like this are common and used for subtle emphasis.

Is the comma before а necessary?

Yes. Russian usually puts a comma before coordinating conjunctions like а, но, да (meaning “but”), однако when they connect two independent clauses (each with its own subject and verb):

Ночью фонарик помог нам найти дорогу, а компас показал правильное направление.

Clause 1: фонарик помог нам найти дорогу
Clause 2: компас показал правильное направление

Each has its own subject and predicate, so the comma before а is required by standard punctuation rules.