Learn Hardcore Swedish: Det finns alltid en liten risk när barnen leker vid sjön. - There is always a small risk when the children play by the lake.

Det finns en risk. – There is a risk (that exists).
Det är en risk. – It is a risk (describing what something is, more like an identity or evaluation).

In your sentence:

Det finns alltid en liten risk…
= There is always a small risk… (a risk exists in that situation).

If you said Det är alltid en liten risk…, it would sound more like evaluating a specific action as “a risky thing”, and it’s less natural here without continuing, e.g. “Det är alltid en liten risk att låta barnen leka där.”

Where can “alltid” go in this sentence? Can I move it?

The most natural place is exactly where it is:

Det finns alltid en liten risk…

You might also hear:

Det finns en liten risk alltid när barnen leker vid sjön.

…but that sounds more marked/emphatic and less neutral.

You cannot put it between the verb and its particle here (there is no particle), and you normally don’t say:

✗ Det alltid finns en liten risk… (wrong word order in a main clause)

So for a neutral sentence, keep:

Det finns alltid en liten risk…

Why is it “en liten risk” and not “ett liten risk” or something else?

In Swedish, nouns have two genders:

en-words (common gender)
ett-words (neuter)

The word risk is an en-word:

en risk – flera risker – risken – riskerna

Adjectives agree with the gender and form:

en liten risk (common gender, singular, indefinite)
ett litet problem (neuter, singular, indefinite)
den lilla risken (common gender, singular, definite)
de små riskerna (plural, definite)

So “en liten risk” is the correct form because risk is an en-word and indefinite singular.

What is the difference between “liten”, “litet”, and “lilla”?

They are different forms of the adjective liten (small, little):

liten – used with en-words, singular, indefinite
- en liten risk, en liten pojke
litet – used with ett-words, singular, indefinite
- ett litet barn, ett litet hus
lilla – used with definite singular (both genders)
- den lilla risken, den lilla pojken, det lilla barnet
små – used with plural
- små risker, de små barnen

Your sentence has an indefinite en-word (en risk), so you use liten.

Why is it “barnen” and not just “barn”?

barn = child / children (indefinite, can be singular or plural depending on context)
barnet = the child
barnen = the children

In “när barnen leker vid sjön”, barnen is definite plural:
“when the children are playing by the lake.”

Using barn here would sound like a general statement about children in general, but Swedish normally adds the definite form when you have a specific, known group in mind (e.g. your kids):

när barnen leker vid sjön – when the children (we have in mind) play by the lake

Why is it “när” and not “om” in “när barnen leker vid sjön”?

Both när and om can be translated as “when” in English, but they are used differently:

när = when (for actual time: every time/whenever/at the time that)
- Det finns alltid en liten risk när barnen leker vid sjön.
  There is always a small risk when the children play by the lake.
om = if (for conditions, not guaranteed to happen)
- Det finns en risk om barnen leker vid sjön.
  There is a risk if the children play by the lake.

Here we are talking about a risk whenever the children do in fact play there, so när is correct.

Can “när” here mean “whenever”, or only “when”?

In this kind of sentence, “när” covers both English meanings:

Det finns alltid en liten risk när barnen leker vid sjön.
= There is always a small risk when the children are playing by the lake.
= There is always a small risk whenever the children play by the lake.

Swedish doesn’t need a separate word for “whenever” here; när handles it from context and the word alltid (always) reinforces the “whenever” idea.

Why is it “vid sjön” and not “i sjön” or “på sjön”?

Different prepositions describe different relations:

vid sjön – by/at the lake, near the shore
- barnen leker vid sjön – the children are playing near the lake.
i sjön – in the lake, in the water
- barnen badar i sjön – the children are swimming in the lake.
på sjön – on the lake, usually out on the water in a boat
- De är ute på sjön i en båt. – They’re out on the lake in a boat.

Since the kids are playing near the lake (not in or on the water), vid is the natural choice.

Why is it “sjön” and not “en sjö”?

en sjö = a lake (indefinite)
sjön = the lake (definite)

In Swedish, if both speaker and listener know which lake is meant (for example, the lake near their house or in their town), you normally use the definite form:

när barnen leker vid sjön – when the children play by the lake (the one we both know about).

Using vid en sjö would sound like “by some lake or other” (not a specific, known one).

Why is “leker” just present tense, not something like “are playing”?

Swedish present tense covers both simple and continuous forms in English:

barnen leker
- the children play
- the children are playing

There is no separate continuous form (are playing) in Swedish grammar; leker does both jobs.
So “när barnen leker vid sjön” can mean:

when the children play by the lake
when the children are playing by the lake

How would I negate this sentence correctly with “inte”?

A natural negation would be:

Det finns inte alltid en liten risk när barnen leker vid sjön.
= There is not always a small risk when the children play by the lake.

Word order:

Det (dummy subject)
finns (verb)
inte (negation)
alltid (adverb)
en liten risk (object)

Putting inte after alltid (Det finns alltid inte…) is not standard Swedish and sounds wrong.

Can I say “Det är alltid en liten risk när barnen leker vid sjön” instead? Is it wrong?

It’s not strictly wrong, but it sounds less natural and a bit off in this exact wording.

Det finns alltid en liten risk…
focuses on the existence of a risk (there is a risk in that situation).
Det är alltid en liten risk…
sounds more like you’re evaluating some specific action as “a small risk”, and the sentence feels incomplete unless you add something like:
- Det är alltid en liten risk att låta barnen leka vid sjön.
  (It is always a small risk to let the children play by the lake.)

So for the original sentence, “Det finns alltid en liten risk…” is the natural choice.

How is “sjön” pronounced? The spelling looks tricky.

Sjön is pronounced with the typical Swedish “sj‑sound”, which is a voiceless, “hissy” sound made further back in the mouth/throat. An approximate breakdown:

sj‑ ≈ a sh-like sound, but more throaty (often written as /ɧ/ in phonetics).
ö = like the vowel in British English “bird” or French “peu”.
n = regular n.

So “sjön” is roughly like “shurn” or “shœn”, but with that special Swedish sj‑sound rather than an English sh.