Ternyata buku catatan saya terbawa ke kantor oleh Ayah.

Ternyata shows a realization, discovery, or unexpected fact. In this sentence, it means something like:

• it turns out
• apparently
• as it happens

So the speaker is not just stating a fact. They are saying they have just found out, or they are surprised to learn, that the notebook ended up at the office with Dad.

Buku catatan saya means my notebook.

Breakdown:

• buku = book
• catatan = notes / note-taking
• buku catatan = notebook / note book
• saya = I / me / my, depending on grammar

In Indonesian, possession usually comes after the noun, so:

• buku saya = my book
• rumah saya = my house
• buku catatan saya = my notebook

So even though saya by itself often means I, after a noun it works like my.

Terbawa comes from bawa, which means to bring or to carry.

The prefix ter- often gives a meaning like:

• happening unintentionally
• happening unexpectedly
• ending up in a certain state

So terbawa here means something like:

• got taken along
• ended up being carried away
• was accidentally brought

That is why this sentence does not sound like a fully planned, deliberate action. It suggests the notebook went along with Dad, probably by mistake or without anyone noticing.

This is an important difference.

• dibawa = was brought / was taken
  This is a regular passive and is more neutral about intention.
• terbawa = got carried along / got taken by accident / ended up being brought
  This often suggests something accidental, unintended, or incidental.

So:

• Buku catatan saya dibawa ke kantor oleh Ayah = My notebook was taken to the office by Dad.
• Buku catatan saya terbawa ke kantor oleh Ayah = My notebook ended up getting taken to the office by Dad, probably unintentionally.

In your sentence, terbawa adds the idea that Dad likely did not mean to take it.

Yes. The focus is on buku catatan saya, the thing affected by the action.

Instead of saying Dad took my notebook to the office, the sentence is built more like:

My notebook got taken to the office by Dad.

That is why the notebook comes first, and Ayah appears later as the agent.

Also, Indonesian passive sentences do not need a separate word like was in English. The passive meaning is often shown by the verb form itself, such as dibawa or, in this case, terbawa.

Oleh means by when introducing the doer in a passive sentence.

So:

• oleh Ayah = by Dad

This tells you who caused the notebook to be taken to the office.

In many Indonesian passive sentences, the agent can be omitted if it is obvious or unimportant. For example:

• Ternyata buku catatan saya terbawa ke kantor.
  = It turns out my notebook got taken to the office.

Adding oleh Ayah makes it clear that Dad was the one who took it along.

Because ke shows movement to a place.

• ke kantor = to the office
• di kantor = at the office / in the office

This sentence is about the notebook being taken to the office, so ke is the correct preposition.

If you said di kantor, the meaning would change. It would describe location, not movement.

Here, Ayah naturally means Dad / my dad.

In Indonesian, family terms like Ayah, Ibu, Kakak, and Adik are often used without an extra possessive when the relationship is already understood from context.

So oleh Ayah is naturally understood as by Dad or by my father.

You could also say oleh ayah saya, but that is more explicit and slightly less natural in a context where the speaker is talking about their own father.

It is capitalized because it is being used like a name or title, similar to Dad in English.

Compare:

• Ayah membawa buku itu. = Dad brought that book.
• ayah saya membawa buku itu. = my father brought that book.

When used as a direct personal reference, Ayah is often capitalized. When used as a common noun, it usually is not.

Yes. Indonesian word order is somewhat flexible, especially with adverbials and passive agents.

For example, these are possible:

• Ternyata buku catatan saya terbawa ke kantor oleh Ayah.
• Ternyata buku catatan saya terbawa oleh Ayah ke kantor.

Both are understandable. The original sentence sounds natural and keeps ke kantor close to the idea of movement, then adds oleh Ayah at the end.

So the sentence order is normal, but not the only possible order.

A straightforward active version would be:

• Ternyata Ayah membawa buku catatan saya ke kantor.

This means It turns out Dad took my notebook to the office.

However, notice the nuance:

• membawa sounds more neutral or deliberate
• terbawa suggests it happened unintentionally

So if you want to keep the accidental idea in an active sentence, you might say something like:

• Ternyata Ayah tanpa sengaja membawa buku catatan saya ke kantor.

That means It turns out Dad accidentally took my notebook to the office.