Çocuğun yanağı kızarmış olmalı, çünkü bütün öğleden sonra güneşte oynadı.

Çocuğun is the noun çocuk + the genitive ending, so it means the child’s or of the child.

In Turkish, when one noun possesses another, the possessor usually takes the genitive:

• çocuk = child
• çocuğun = the child’s

There is also a sound change here:

• çocuk
  • -un → çocuğun

The final k often softens to ğ when a vowel-initial suffix is added.

Because yanağı means his/her cheek or the cheek in a possessive construction.

This is:

• yanak = cheek
• yanağı = his/her cheek

In çocuğun yanağı, Turkish marks possession on both words:

• çocuğun = of the child
• yanağı = his/her cheek

So together:

• çocuğun yanağı = the child’s cheek

Again, the final k softens:

• yanak
  • -ı → yanağı

Yes. This is a very common Turkish pattern called the genitive-possessive construction.

Turkish often marks possession twice:

• the possessor gets the genitive
• the possessed thing gets a possessive suffix

So:

• adamın arabası = the man’s car
• öğretmenin kitabı = the teacher’s book
• çocuğun yanağı = the child’s cheek

This is one of the biggest structural differences from English, where only the child’s is marked.

Kızarmış comes from kızarmak, which means to become red, to redden, or sometimes to blush.

So kızarmış means something like:

• has turned red
• became red
• apparently turned red

The suffix -mış / -miş / -muş / -müş often adds a sense of:

• indirect knowledge
• result
• inference
• apparently / it seems

In this sentence, the idea is not that the speaker directly watched the cheek turn red. The speaker is concluding it from the child’s having played in the sun.

Because kızarmış olmalı expresses deduction: it must have turned red.

Compare:

• kızardı = it turned red / became red
  
  • more direct, plain past
• kızarmış = it seems it turned red / apparently it turned red
• kızarmış olmalı = it must have turned red

So -mış olmalı is a very common way to say must have done in Turkish.

That fits the logic of the sentence:

• He played in the sun all afternoon,
• so his cheek must have become red.

Olmalı comes from olmak (to be / to become) + -malı / -meli.

This ending can mean:

• should
• must
• ought to

But in this sentence it is not about obligation. It is about probability or inference.

So:

• olmalı = must be
• kızarmış olmalı = must have turned red

This is sometimes called epistemic must: the speaker is making a logical conclusion.

Because oynadı presents the reason as a straightforward fact:

• oynadı = he/she played

The suffix -dı / -di / -du / -dü is the direct past or definite past. It is used when the speaker treats the event as known or established.

So the structure is:

• Çocuğun yanağı kızarmış olmalı = The child’s cheek must have turned red
• çünkü bütün öğleden sonra güneşte oynadı = because he/she played in the sun all afternoon

The first clause is an inference.
The second clause gives the known reason.

Bütün öğleden sonra means all afternoon.

Breakdown:

• bütün = all / whole
• öğleden sonra = afternoon

Together:

• bütün öğleden sonra = the whole afternoon / all afternoon

Time expressions in Turkish often work adverbially without an extra case ending, especially when they answer when? or how long?

Examples:

• bütün gün = all day
• bütün gece = all night
• iki saat bekledim = I waited for two hours

So this phrase is functioning like an adverb of time.

Güneşte is güneş (sun) + the locative ending:

• güneş = sun
• güneşte = in the sun / under the sun / out in the sun

The locative suffix has several forms:

• -de / -da / -te / -ta

Here it becomes -te because:

1. güneş has front vowels, so the vowel is e
2. the final consonant ş is voiceless, so the suffix uses t

So:

• güneş + te → güneşte

In natural English, this phrase is usually translated as in the sun.

Yes, English often says his cheeks got red, especially in this kind of context. Turkish can do that too, but here the sentence uses the singular:

• yanağı = his/her cheek

This simply focuses on a cheek or the cheek as a body part. Turkish and English do not always match in singular/plural choices.

If you wanted cheeks, you could say something like:

• yanakları = his/her cheeks
• çocuğun yanakları = the child’s cheeks

So the singular here is grammatically normal; it is just a different way of expressing the idea.

Because Turkish normally prefers verb-final word order.

A very common default pattern is:

• Subject + Object/Other elements + Verb

So:

• bütün öğleden sonra güneşte oynadı
  literally: all afternoon in-the-sun played

This is normal Turkish syntax. English puts the verb much earlier, but Turkish usually keeps it toward the end of the clause.

Çünkü means because.

It introduces the reason for the conclusion:

• Çocuğun yanağı kızarmış olmalı = The child’s cheek must have turned red
• çünkü bütün öğleden sonra güneşte oynadı = because he/she played in the sun all afternoon

So the sentence structure is:

• statement/conclusion
• çünkü
• reason

This is very similar to English because.

Not directly, and that is normal in Turkish.

Oynadı already contains a third-person singular meaning:

• oynadı = he/she played

Turkish often omits pronouns like o (he/she/it) when the meaning is clear from context.

Here, the understood subject is the child mentioned earlier:

• çünkü bütün öğleden sonra güneşte oynadı
• because he/she played in the sun all afternoon

So the sentence does not need an explicit o.