Learn Hardcore Swedish: Han säger att barnen blir tryggare varje gång de har en liten modevisning hemma. - He says that the children become more confident every time they have a little fashion show at home.

In this context (doing a little fashion show at home), tryggare is most naturally understood as more confident / more at ease with themselves, not mainly about physical safety.

Why do we use blir here instead of är, as in barnen blir tryggare?

Bli means to become or to get.

Barnen blir tryggare focuses on a change over time:

the children become more confident
the children get more secure

If you said barnen är tryggare, it would sound more like a static comparison (e.g. the children are more secure than before / than others), but without clearly expressing the process of change.

You could also say:

Barnen känner sig tryggare – the children feel more secure

But bli is the most natural when you want to say that something gradually increases or changes repeatedly, as in every time they do a fashion show, they become a bit more confident.

Why do we need att in Han säger att barnen blir tryggare?

Att here is a subordinating conjunction or complementizer, like that in English:

Han säger att barnen blir tryggare.
He says that the children become more confident.

In Swedish, when you report what someone says, thinks, believes, etc., you usually introduce the subordinate clause with att:

Hon tror att det blir bra. – She thinks (that) it will be good.
Jag vet att han kommer. – I know (that) he is coming.

In spoken English you can often drop that; in Swedish you normally keep att in standard written language. Omitting att is possible in informal speech but is less standard.

Why is the word order att barnen blir tryggare and not att blir barnen tryggare?

Swedish has different word order rules for:

main clauses (independent sentences)
subordinate clauses (introduced by att, när, eftersom, som, etc.)

In a main clause, Swedish is usually V2 (the verb comes in second position):

Barnen blir tryggare. – The children become more confident.
Idag blir barnen tryggare. – Today the children become more confident.

In a subordinate clause, introduced by att, the verb does not move to second position the same way. Instead, the order is usually:

subject – verb – rest

So you get:

att barnen blir tryggare (correct)
not
att blir barnen tryggare (incorrect in standard Swedish)

So:

Han säger att barnen blir tryggare.

Why is it barnen and then de? Are they referring to the same children?

Yes, barnen and de refer to the same group.

barn = child/children (indefinite form)
barnen = the children (definite plural)

Later in the sentence, de means they, and it refers back to barnen:

Han säger att barnen blir tryggare varje gång de har en liten modevisning hemma.
- barnen = the children
- de = they (the children)

So the structure is:

He says that the children become more confident every time *they have a little fashion show at home.*

What is the difference between de, dem, and dom in Swedish, and why is de used here?

Standard written Swedish distinguishes:

de – subject form (like English they)
dem – object form (like English them)

Example:

De ser dem. – They see them.

In your sentence:

... varje gång de har en liten modevisning ...
Here, de is the subject of har, so de (not dem) is correct.

Dom is the common spoken pronunciation of both de and dem. In informal writing, people often write dom for everything:

Dom ser dom.

But in standard/formal writing you should still use de (subject) and dem (object).

Why is it en liten modevisning and not ett litet modevisning? How does liten work?

Two things are important here:

Gender of the noun
- modevisning is an en-word: en modevisning
  So you must use en, not ett.
Adjective agreement with an en-word in singular, indefinite, before the noun:
- en liten modevisning – a little fashion show

The adjective liten has special forms:

en liten bil – a little car
ett litet hus – a small house
små bilar / små hus – small cars / small houses

So:

en liten modevisning (correct)
ett litet modevisning (wrong, because modevisning is not an ett-word)

What exactly does modevisning mean, and is it a compound word?

Yes, modevisning is a compound noun:

mode – fashion
visning – showing, display, viewing

Put together:

modevisning = fashion show

This kind of compounding is very common in Swedish, and it’s usually written as one word:

modevisning – fashion show
fotbollsmatch – football match
sommarstuga – summer cottage

So en liten modevisning is literally a small fashion-show.

Why is hemma used without any preposition (no i hemma or på hemma)?

Hemma is an adverb, not a noun, so it doesn’t usually take a preposition in Swedish.

hemma – at home (location)
hem – (to) home (direction)

Examples:

Jag är hemma. – I am at home.
Jag går hem. – I am going home.

So:

... en liten modevisning hemma. – a little fashion show at home.

If you use the noun hem (home as a thing), you would then need a preposition and a definite ending:

i hemmet – in the home
But that sounds more formal and less natural here than just hemma.

Can hemma go earlier in the phrase, like har hemma en liten modevisning?

The most natural word order is:

... varje gång de har en liten modevisning hemma.

You can say:

... varje gång de har hemma en liten modevisning.

but it sounds more marked and less idiomatic, and may shift the emphasis slightly onto hemma (as in: at home, they have a little fashion show).

In everyday Swedish, place adverbs like hemma usually come after the object:

De har fest hemma. – They have a party at home.
Vi äter middag hemma. – We eat dinner at home.

So har en liten modevisning hemma is the preferred order.

Why are all the verbs in the present tense (säger, blir, har) even though this can describe repeated actions over time?

Swedish uses the present tense for:

actions happening now
habits and repeated actions
general truths

Here it’s a habitual situation: it happens repeatedly:

Han säger att barnen blir tryggare varje gång de har en liten modevisning hemma.
= He says that the children become more confident every time they have a little fashion show at home.

This is the same as English, which also uses present tense here (says / become / have).

If you wanted this in the past, you would change all relevant verbs to past:

Han sa att barnen blev tryggare varje gång de hade en liten modevisning hemma.
– He said that the children became more confident every time they had a little fashion show at home.

What is the difference between varje gång and när here? Could you say när de har en liten modevisning hemma instead?

Both are possible, but they don’t feel exactly the same.

varje gång de har ...
Literally every time they have ...
→ Emphasises that this happens repeatedly, on many occasions.
när de har ...
Literally when they have ...
→ More neutral; can mean generally when(ever), but doesn’t highlight each separate occurrence as strongly.

In this sentence, varje gång fits very well because the idea is that each time they do a fashion show, the children become a bit more confident.

You can say:

Han säger att barnen blir tryggare när de har en liten modevisning hemma.

It’s still correct and natural, but the version with varje gång makes the repeated, step‑by‑step effect clearer.