Learn Hardcore Indonesian: Psikolog sekolah menuliskan beberapa saran di kertas dan membacakan isinya dengan pelan. - The school psychologist writes some advice on paper and reads it out slowly.

Psikolog sekolah literally means school psychologist.
In Indonesian, nouns usually appear without articles like a, an, or the. Context tells you whether it means a school psychologist or the school psychologist.

So Psikolog sekolah here is naturally understood as the school psychologist because we are talking about a specific person in the situation.

Is there a difference between menuliskan and menulis?

Yes, there is a nuance difference:

menulis = to write (basic verb)
- Psikolog sekolah menulis beberapa saran. → The school psychologist wrote some suggestions.
menuliskan = to write something down, often with more focus on the object being produced or on the beneficiary (who it is for).

In this sentence, menuliskan beberapa saran di kertas suggests writing the suggestions down on paper, emphasizing the act of putting them onto the paper (not just composing them in general).

In many everyday contexts, menulis and menuliskan can both sound natural and are often interchangeable, with only a small nuance difference.

What is the difference between membaca and membacakan?

membaca = to read (for yourself or in general)
membacakan = to read something aloud for someone (there is an implied listener/beneficiary)

In membacakan isinya dengan pelan, the -kan form suggests the psychologist is reading the contents out loud to someone (for example, to a student, parent, or teacher), not just reading silently.

If you said membaca isinya dengan pelan, it could still be understood, but it sounds more like reading for oneself, not necessarily for someone else.

What does isinya mean, and what is the function of -nya here?

isi = content, contents
-nya has several functions, and here it works as a possessive pronoun: its content / the content of it.

So isinya = its contents or the contents (of what was written on the paper).

It most naturally refers to the suggestions written on the paper, i.e. the contents of the paper. Context decides the exact reference, but listeners will understand it that way.

Why is it di kertas and not di atas kertas?

Both are possible, with a nuance:

di kertas = literally on paper, but idiomatically can mean on/into the paper without focusing on physical position
di atas kertas = more literally on top of the paper, slightly more physical/locational

In many contexts, Indonesians say di kertas to mean on (the) paper when talking about writing. Menuliskan beberapa saran di kertas is perfectly natural and common.

How should I understand beberapa saran? Is saran countable?

beberapa means some / several, and it normally goes with countable items.

saran = advice / suggestion. Indonesian does not mark plural with -s like English, so:

saran can mean advice (in general)
with beberapa saran, it clearly means several suggestions.

You do not need to say saran-saran here; beberapa saran already shows plurality.

Can I say pelan-pelan instead of dengan pelan? Are they different?

Yes, you can, with slightly different style:

dengan pelan = slowly, in a slightly more neutral or formal style
pelan-pelan = slowly, often a bit more colloquial or emphatic

So:

membacakan isinya dengan pelan
membacakan isinya pelan-pelan

Both mean read the contents slowly. Pelan-pelan is very common in speech.

You might also hear dengan perlahan or perlahan-lahan, which have a similar meaning and are slightly more formal/standard.

Can pelan be used without dengan? For example, membacakan isinya pelan?

Yes. Indonesian often uses adjectives directly as adverbs without dengan:

membacakan isinya pelan = read its contents slowly
berjalan cepat = walk fast
berbicara jelas = speak clearly

So you can say:

membacakan isinya dengan pelan
membacakan isinya pelan
membacakan isinya pelan-pelan

All are acceptable, with very similar meanings.

Is sekolah working like an adjective in psikolog sekolah?

Functionally, yes, but grammatically it is still a noun. Indonesian often uses Noun + Noun to form a noun phrase where the second noun describes or specifies the first:

psikolog sekolah = school psychologist
guru bahasa = language teacher
dokter hewan = veterinarian (animal doctor)

The second noun (sekolah) narrows down what kind of psikolog it is. There is no extra word like of or for; it is simply juxtaposed.

How do we know this sentence is in the past? There is no tense marker.

Indonesian verbs do not change form for tense. Time is usually understood from:

context, or
time words like sudah, tadi, kemarin, besok, etc.

In isolation, Psikolog sekolah menuliskan... dan membacakan... could be translated as:

The school psychologist writes ... and reads ... (habitual), or
The school psychologist wrote ... and read ...

If you add sudah it clearly marks it as completed:

Psikolog sekolah sudah menuliskan beberapa saran... → has already written / wrote

In your learning context, they probably gave you a past-tense translation simply because that is the most natural way to describe this kind of event in English.

Could we add who the suggestions are for, using menuliskan or membacakan?

Yes, the -kan form fits very well with a beneficiary phrase:

Psikolog sekolah menuliskan beberapa saran di kertas untuk murid itu.
→ The school psychologist wrote down some suggestions on paper for that student.
Psikolog sekolah membacakan isinya kepada orang tua murid.
→ The school psychologist read the contents to the student’s parents.

The -kan often implies that the action is done for someone’s benefit, so adding untuk / kepada + person is very natural.

Can I replace dan with lalu or kemudian? Would the meaning change?

You can, with a small nuance shift:

dan = and (just joins the two actions)
lalu / kemudian = and then, afterwards (emphasizes sequence)

So:

... menuliskan beberapa saran di kertas dan membacakan isinya ...
→ wrote some suggestions on paper and read them
... menuliskan beberapa saran di kertas lalu/kemudian membacakan isinya ...
→ wrote some suggestions on paper and then read them

All are grammatical; lalu/kemudian just makes the order of actions more explicit.

Where else can I put dengan pelan in the sentence? Is word order flexible?

Word order is fairly flexible for adverbials like dengan pelan, as long as it remains clear:

Psikolog sekolah menuliskan beberapa saran di kertas dan membacakan isinya dengan pelan.
Psikolog sekolah menuliskan beberapa saran di kertas dan dengan pelan membacakan isinya.
Psikolog sekolah, dengan pelan, membacakan isinya. (if the writing part is already known)

All sound natural. You cannot put dengan pelan in the middle of membacakan and isinya (for example: membacakan dengan pelan isinya) is still acceptable in speech, but the most neutral position is after the whole verb phrase: membacakan isinya dengan pelan.