Learn Hardcore Norwegian: Begge av barna mine liker naturfag, men bare én av dem liker matte. - Both of my children like science, but only one of them likes math.

Begge av barna mine = both of my children (literally: both of the children mine).
Begge barna mine = both my children. This is also completely natural and very common.
Begge mine barn is also grammatically correct and means the same in everyday use.

Nuances (small, and often not important for learners):

Begge barna mine / begge av barna mine sound a bit more neutral and conversational.
Begge mine barn can sound a little more formal or emphatic on mine (my).

In practice, all three can be used here with almost no difference in meaning.

Why is it barna mine and not mine barn? Are both correct?

Yes, both are correct Norwegian:

barna mine – noun in definite form (barna = the children) + possessive.
- Feels very natural in spoken language.
- Implies a specific, known group: the children that are mine.
mine barn – possessive first, noun in indefinite form.
- Slightly more formal or written style in many people’s ears.
- Often feels a bit more general or slightly more emphasis on mine (my).

In your sentence, you could say:

Begge av barna mine liker naturfag… (as given)
Begge av mine barn liker naturfag…

Both are fine and idiomatic.

Why is én written with an accent here? What is the difference between én and en?

Norwegian uses én (with accent) to make it clear that we mean the number one, not the indefinite article (a/an).

én = the numeral one (especially when you want to stress “one, not two or more”).
en = usually the article a/an for masculine nouns, but can also be the pronoun one/someone.

In bare én av dem liker matte, the accent shows:

We mean exactly one of them, not just some unspecified en.

Pronunciation:

In careful speech, both are pronounced similarly, but én is often stressed more clearly because you are emphasizing the number.

Why is it av dem and not av de? What is the rule for de vs dem here?

Norwegian distinguishes between subject and object forms:

de = subject form (they).
- De liker matte. – They like math.
dem = object form (them).
- Jeg liker dem. – I like them.
- én av dem – one of them → av takes an object.

In én av dem, dem is the object of the preposition av, so dem is the only correct standard written form.

Note: In some dialects, people may pronounce it like de in speech, but in writing it should be dem in this position.

Why is the verb liker the same in Begge av barna mine liker… and én av dem liker… even though one subject is plural and the other is singular?

Norwegian verbs do not change for person or number in the present tense.

jeg liker – I like
du liker – you like
han/hun liker – he/she likes
vi liker – we like
dere liker – you (plural) like
de liker – they like

So:

Begge av barna mine liker naturfag – Both of my children like science.
Bare én av dem liker matte – Only one of them likes math.

The verb liker stays the same in both sentences.

What exactly does naturfag mean? Is it the same as English science?

Naturfag is the name of the school subject that covers the natural sciences in Norwegian schools (typically biology, physics, chemistry, etc.).

In a school context, naturfag is usually translated as science.
It does not normally include social sciences (history, sociology, etc.).
As a school subject, it’s used without an article:
- Barna liker naturfag. – The children like science (as a subject).

What does matte mean, and is it informal? Could I say matematikk instead?

matte is the everyday, informal word for the subject mathematics.
The full, more formal word is matematikk.

Both are correct:

Bare én av dem liker matte. – very natural, informal/neutral.
Bare én av dem liker matematikk. – more formal or schoolish style.

Teachers, students, and parents very often say matte in everyday conversation.

Why is there a comma before men? Is that always required?

In standard Norwegian punctuation:

You normally put a comma before men when it connects two main clauses (two parts that both have their own subject and verb).

In your sentence:

Begge av barna mine liker naturfag → main clause.
bare én av dem liker matte → another main clause.

Therefore:

Begge av barna mine liker naturfag, men bare én av dem liker matte.

When men only connects two smaller phrases (not full clauses), you don’t use a comma:

Han liker både naturfag og matte, men ikke fysikk.
(Here the part after men is not a full clause with its own subject and verb.)

Could I leave out av dem and just say …men bare én liker matte?

Yes, grammatically that is possible:

…men bare én liker matte.

However:

bare én liker matte is more ambiguous by itself: only one person (whoever that is) likes math.
bare én av dem liker matte makes it explicit that the “one” comes from the previously mentioned group (your children).

In context, native speakers often keep av dem here, because it clearly ties the second clause to barna mine.

Why are there no articles before naturfag and matte? Why not liker naturfaget or liker matten?

In Norwegian, certain nouns are typically used without an article when you speak about them in a general way:

School subjects: naturfag, matte, engelsk, historie
Languages: norsk, spansk, tysk
Some activities: fotball, sjakk (when you mean the sport/game in general)

So:

Barna liker naturfag. – The children like science (as a subject in general).
Bare én av dem liker matte. – Only one of them likes math (in general).

If you say naturfaget or matten, you are referring to a specific course/instance:

Han liker ikke naturfaget i år. – He doesn’t like the science course this year.
(That particular class/teacher, not the subject in general.)