Learn Hardcore French: Ils se sentent plus équilibrés quand ils passent une journée entière dehors sans que leurs téléphones ne sonnent. - They feel more balanced when they spend a whole day outside without their phones ringing.

se sentir + adjective = to feel + adjective
- Ils se sentent plus équilibrés. → They feel more balanced.
sentir without se usually means to smell or to sense something external:
- Je sens le café. → I smell coffee.

You cannot use être (sont) here, because ils sont plus équilibrés would mean they are more balanced as an objective fact, not how they feel. The French sentence is about their subjective feeling, so se sentir is correct.

Why is équilibrés masculine plural, and what is it agreeing with?

Adjectives in French agree in gender and number with the noun or pronoun they describe.

Subject: ils → masculine plural.
Adjective: équilibré changes to équilibrés (masculine plural: add s).

So:

Il se sent équilibré. → He feels balanced.
Elle se sent équilibrée. → She feels balanced.
Ils se sentent équilibrés. → They feel balanced. (group of at least one man)
Elles se sentent équilibrées. → They feel balanced. (all women)

In speech, the final -s of équilibrés is silent, but the agreement is important in writing.

What exactly does plus mean here, and could it ever mean no longer in this sentence?

Here plus is the comparative more:

plus équilibrés = more balanced.

Plus can mean no longer / no more in negative structures with ne (for example, je ne fume plus = I no longer smoke), but that is not the case here:

There is no ne ... plus pair around the verb se sentent.
The sentence pattern is se sentir plus + adjective = to feel more + adjective.

So in this sentence, plus only means more, not no longer.

Why is it quand ils passent and not a future tense like quand ils passeront?

French often uses the present tense for general truths, habits, and repeated actions, where English might use the present as well:

Ils se sentent plus équilibrés quand ils passent une journée entière dehors.
→ They feel more balanced when they spend a whole day outside.

This describes a general habit, not a single future event.

If you were talking about a specific future situation, you could use the future:

Ils se sentiront plus équilibrés quand ils passeront une journée entière dehors.
→ They will feel more balanced when they spend a whole day outside.

But in the original sentence, it’s about what is usually true, so the present passent is natural.

What is the difference between une journée entière and un jour entier or toute la journée?

All relate to a whole day, but there are nuances:

une journée entière
- Focuses on the duration of the day as a stretch of time.
- Often used when talking about how long something lasts or how you spend that time.
un jour entier
- More neutral; often used in counting days: pendant un jour entier = for a whole day.
- In many contexts it overlaps with une journée entière, but journée tends to emphasize the daytime period / span.
toute la journée
- Means all day long / the whole day (more like a definite day).
- Often used when the timeframe is already identified:
  - Ils sont restés dehors toute la journée. → They stayed outside all day.

Here une journée entière suggests spending an entire day (as a block of time) outside, which fits well with the idea of feeling more balanced.

Why is entière feminine singular?

Entière is an adjective describing journée:

journée is feminine singular → une journée.
So the adjective must also be feminine singular → entière (with final -e).

Patterns:

Masculine singular: entier (un jour entier)
Feminine singular: entière (une journée entière)
Masculine plural: entiers
Feminine plural: entières

Why is it dehors instead of something like à l’extérieur or en plein air?

Dehors is a very common, everyday adverb meaning outside / outdoors. It’s short and natural here.

dehors → general outside, very common in speech and writing.
à l’extérieur → a bit more formal or spatial (outside of a building, a place, an area).
en plein air → in the open air, often used for activities done outdoors: un concert en plein air.

You could say:

… quand ils passent une journée entière à l’extérieur. (OK, slightly more formal)
… quand ils passent une journée entière en plein air. (puts more emphasis on fresh air / open air)

But dehors is the most straightforward and colloquial choice.

Why do we use sans que here, and what does it do to the verb that follows?

Sans que means without (the fact) that / without [something] happening. In French, sans que is one of the conjunctions that almost always requires the subjunctive.

So:

sans que + subjunctive
sans que leurs téléphones ne sonnent → without their phones ringing.

Even though English uses a gerund (ringing), French uses a full clause introduced by sans que, and that triggers the subjunctive sonnent.

If sans que takes the subjunctive, how can I tell that sonnent is subjunctive and not just present indicative?

In modern French, many present-tense subjunctive forms look identical to the present indicative, especially in the ils/elles form.

ils sonnent (indicative)
qu’ils sonnent (subjunctive)

They are written and pronounced the same. You know it’s subjunctive because of the structure:

After sans que, the verb must be in the subjunctive.
The mood (indicative vs subjunctive) is determined by the preceding conjunction, not by the verb form itself in this case.

So grammatical analysis tells you it’s subjunctive, even though the form looks the same.

Why is there a ne before sonnent even though the sentence is not negative?

This ne is an example of ne explétif (also called ne pléonastique). It does not make the sentence negative.

It often appears after certain conjunctions or expressions that imply fear, prevention, doubt, or absence, such as:

avant que
de peur que, de crainte que
sans que, especially in more formal or careful French.

So:

sans que leurs téléphones ne sonnent ≈ without their phones ringing
It is not without their phones not ringing.

The ne here is stylistic/emphatic, not a logical negation.

Is the ne in ne sonnent optional? Can I say sans que leurs téléphones sonnent?

Yes, in modern French, the ne explétif is often omitted in everyday speech and informal writing.

Formal / careful: sans que leurs téléphones ne sonnent
Neutral / common: sans que leurs téléphones sonnent

Both are grammatically acceptable. Leaving out ne is very common; using it sounds a bit more formal or literary.

Could I add pas and say sans que leurs téléphones ne sonnent pas?

No, you should not add pas here.

ne in this sentence is not a real negation; it’s ne explétif.
Adding pas would create a true negation (ne … pas) and give a different meaning: without their phones not ringing, which is logically confusing.

Correct forms:

sans que leurs téléphones ne sonnent (with explétif, more formal)
sans que leurs téléphones sonnent (without explétif, more neutral)

But sans que leurs téléphones ne sonnent pas is incorrect for the intended meaning.

Why is it leurs téléphones and not leur téléphone?

Both are possible in French, but they have different meanings:

leurs téléphones = their phones (at least two phones in total).
- Suggests the group as a whole has several phones (usually one each).
leur téléphone = their phone (one phone shared, or you’re not specifying number per person but talking about the possession collectively).

In practice:

leurs téléphones fits the idea that each person likely has their own phone.
sans que leur téléphone sonne would sound like there is one single phone for all of them, which is less natural in modern contexts.

So leurs téléphones is the logical choice here.