En octobre, les enfants choisissent un déguisement pour Halloween.

French usually uses en with months, seasons, and years when you mean in a time period:

• en octobre = in October
• en été = in summer
• en 2026 = in 2026

So en octobre is the normal way to say in October.

French can place a time expression at the beginning of the sentence to set the scene, just like English:

• En octobre, les enfants choisissent un déguisement...
• Les enfants choisissent un déguisement en octobre...

Both are possible. Starting with En octobre simply emphasizes when it happens.

The comma is also normal here because the sentence begins with a time phrase.

Les enfants means the children, but in French it can also refer to children in general in a broad, generic sense.

So here, les enfants choisissent un déguisement pour Halloween can mean something like:

• children choose a costume for Halloween
• or the children choose a costume for Halloween

French often uses les where English might use the or no article at all for general statements.

By contrast, des enfants usually means some children.

The base verb is choisir = to choose.

Here it is conjugated in the present tense for ils/elles because les enfants is plural:

• je choisis
• tu choisis
• il/elle choisit
• nous choisissons
• vous choisissez
• ils/elles choisissent

Since les enfants = they, the correct form is choisissent.

It is the regular third-person plural present-tense ending for many -ir verbs like choisir.

For this verb family:

• singular: choisis, choisis, choisit
• plural: choisissons, choisissez, choisissent

So -issent here tells you the subject is they.

No. In normal French pronunciation, the -ent ending of third-person plural verbs is usually silent.

So choisissent is pronounced roughly like shwa-zee-ss.

That means:

• il choisit
• ils choisissent

do not sound exactly the same, but the final -ent itself is not pronounced.

Un déguisement means a costume or a disguise.

It uses un because déguisement is a masculine singular noun.

So:

• un déguisement = a costume
• le déguisement = the costume
• des déguisements = costumes / some costumes

For Halloween, déguisement is often the more natural word because it means a costume used for dressing up or disguising yourself.

Costume in French often means:

• a suit
• formal clothing
• or, in some contexts, a stage/theatrical costume

So for Halloween, déguisement is usually the safer and more idiomatic choice.

Pour here means for in the sense of for the occasion of Halloween.

So:

• un déguisement pour Halloween = a costume for Halloween

This is the natural preposition because the costume is intended for that event.

Holiday names in French often appear without an article, especially after a preposition:

• pour Halloween
• à Noël
• à Pâques

So Halloween here works like a proper name of a holiday, and no article is needed.

The present tense in French can do both, depending on context.

So this sentence could mean:

• a general/habitual idea: In October, children choose a costume for Halloween
• or a current description in a lesson/story context

Without more context, it often sounds like a general truth or usual activity.

Yes, but it changes the meaning slightly.

• un déguisement suggests each child chooses a costume, viewed individually in a general way.
• des déguisements focuses more on costumes in the plural.

Both can work, but un déguisement is very natural in French when speaking about what each member of a group typically chooses.

The main structure is:

• En octobre = time expression
• les enfants = subject
• choisissent = verb
• un déguisement = direct object
• pour Halloween = prepositional phrase showing purpose/occasion

So the core sentence is:

• les enfants choisissent un déguisement

And the other parts add time and context.