Learn Hardcore Swedish: Barnen leker vid sjön, men mamman går en promenad på en liten väg i skogen. - The children are playing by the lake, but the mother goes for a walk on a small road in the forest.

Barn is the basic form and can mean either child (singular) or children (plural), depending on context.
To say the children, Swedish adds a definite ending:

ett barn = a child
barnet = the child
barn = children
barnen = the children

So Barnen leker… means The children are playing…. If you said just Barn leker…, it would sound incomplete or generic, like Children play… (in general), not about specific children in this situation.

Why is it leker and not spelar for play?

Swedish distinguishes between two verbs for to play:

leka – general play, especially children playing, free play, imaginary play:
- Barnen leker. = The children are playing.
spela – playing a game, a sport, or an instrument:
- spela fotboll (play football), spela gitarr (play guitar), spela ett spel (play a game)

Here the children are just playing in general, so leker is correct. Barnen spelar vid sjön would usually suggest they are playing some kind of game or sport there.

Why is leker translated as “are playing”? There’s no “är” in Swedish.

Swedish does not use a separate continuous form like English am/is/are playing.
The simple present form covers both:

Barnen leker. = The children play. / The children are playing.

Context decides whether English should use simple present or present continuous. Adding är (är leker) is incorrect; Swedish just uses leker.

What does vid sjön mean exactly, and how is it different from i sjön or på sjön?

vid sjön = by / at / near the lake (on the shore or close to it)
i sjön = in the lake (in the water)
på sjön usually = out on the lake (typically in a boat)

So Barnen leker vid sjön means they are near the water, not in it and not out on a boat.

Why is there a comma before men? Is it required?

Yes, in Swedish you normally put a comma before men when it joins two main clauses:

Barnen leker vid sjön, men mamman går en promenad…

Each side could stand as its own sentence:

Barnen leker vid sjön.
Mamman går en promenad…

So the comma before men is standard and natural here, similar to English: The children are playing by the lake, but the mother is going for a walk…

Why is the word order men mamman går en promenad and not men går mamman en promenad?

After men, we start a new main clause, and Swedish uses verb-second word order:

First position: usually subject (mamman)
Second position: finite verb (går)

So: men mamman går en promenad
Putting går first (men går mamman…) would sound marked or poetic; in normal speech and writing, subject–verb after men is correct.

What does the phrase går en promenad literally mean, and is it the normal way to say “go for a walk”?

Literally, går en promenad is walks a walk. It’s a very common idiomatic way to say go for a walk:

Mamman går en promenad. = The mother goes for a walk.

Other natural options:

Mamman tar en promenad. (also fine)
Mamman promenerar. (more “she is walking / taking a walk” as a standalone verb)

All are correct; gå en promenad is very typical and conversational.

Why do we say på en liten väg and not i en liten väg?

For roads, streets, and paths, Swedish usually uses på (on):

på vägen = on the road
på gatan = on the street
på stigen = on the path

i (in) would only work if you were physically inside something, like i en tunnel (in a tunnel) or i en korridor (in a corridor). So en promenad på en liten väg = a walk on a small road.

Why is it en liten väg and not en litet väg or en små väg?

The adjective liten changes with gender and number:

Common gender, singular: en liten väg (a small road), en liten bil
Neuter, singular: ett litet hus (a small house)
Plural (both genders): små vägar, små hus

Since väg is en-word (common gender) and singular, you must use liten: en liten väg.
litet väg and en små väg are ungrammatical.

Why is it i skogen and not i en skog?

i skogen = in the forest / in the woods (a specific forest that speaker and listener can identify from context)
i en skog = in a forest (some forest, not specified which one)

In the sentence, we are talking about a concrete scene: the children, the lake, the mother, so the forest fits that pattern: i skogen. Using i en skog would feel more vague or general.

Why is it mamman and not mamma? Is there a nuance?

mamma = (a) mother / mom, indefinite
mamman = the mother / the mom, definite

Using mamman signals that this is a specific, known mother (very likely the children’s mother). It matches Barnen (the children) and sjön (the lake) and skogen (the forest) – all definite. Saying men mamma går en promenad… would sound more like you started a brand-new topic without clearly linking her to the scene.

Could we use medan instead of men to highlight that these things happen at the same time?

Yes, you could say:

Barnen leker vid sjön medan mamman går en promenad på en liten väg i skogen.

medan = while, focusing on simultaneity.
men = but, focusing on contrast (the children are doing one thing, the mother something different). Both may be true at the same time, but men highlights the difference, medan highlights the timing.