U školi nam je obično lakše kad je na ploči sve jasno napisano i kad u dnevniku nema novih napomena.

This is about prepositions and case.

• u školi = in / at school
• na ploči = on the board
• u dnevniku = in the register / class book

After u and na, when you are talking about a location rather than movement, Croatian uses the locative case:

• škola → u školi
• ploča → na ploči
• dnevnik → u dnevniku

If there were movement toward a place, you would usually get the accusative instead, for example u školu = to school / into the school.

Also, u školi often means at school in a general sense, not only physically inside the building.

Nam is the unstressed dative form of mi = we / us.

Here it means to us or for us:

• nam je lakše = it is easier for us

Croatian very often uses the dative with feelings, comfort, difficulty, and similar ideas:

• lako mi je = it is easy for me
• teško mu je = it is hard for him
• drago nam je = we are glad

So nam is not a direct object here. It marks the people experiencing the situation.

Lakše is the comparative form meaning easier.

In sentences like this, Croatian commonly uses this form in an impersonal pattern:

• nam je lakše = it is easier for us

There is no specific masculine or feminine noun that lakše has to agree with, so you do not get lakši or lakša here.

A useful way to think of it is:

• lako = easy
• lakše = easier

In this kind of sentence, Croatian works a lot like English it is easier.

Not an explicit one.

This is an impersonal construction. Croatian often says things like:

• teško mi je
• lako nam je
• bolje je
• jasno je

These do not need a normal subject like on, ona, or to. In English, we often insert it:

• it is usually easier for us

In Croatian, that it is usually not expressed. The kad... clauses explain the situation in which it is easier.

Yes, Croatian word order is fairly flexible, and obično can move.

The sentence has:

• U školi nam je obično lakše...

But you could also hear:

• Obično nam je u školi lakše...
• Nam je u školi obično lakše...

The original order sounds natural because it sets the scene first (u školi), then the experiencer (nam), then the frequency (obično), then the main idea (lakše).

So the position of obično is natural, but not the only possible one.

Both kad and kada mean when.

The difference is mostly stylistic:

• kad = shorter, very common, everyday
• kada = a bit fuller, sometimes slightly more formal or emphatic

So:

• kad je na ploči...
• kada je na ploči...

Both are correct. In normal speech and writing, kad is extremely common.

Because there are two parallel when-clauses:

• kad je na ploči sve jasno napisano
• i kad u dnevniku nema novih napomena

Repeating kad makes the structure clearer and more balanced. It is similar to English:

• when everything is clearly written on the board and when there are no new notes...

In some contexts Croatian can omit the second kad, but repeating it is very natural here.

Here jasno functions as an adverb, meaning clearly.

So:

• jasno napisano = clearly written

It describes how something is written.

This can confuse learners because jasno can also look like the neuter form of the adjective jasan = clear. But in this sentence the meaning is adverbial:

• not clear written
• but clearly written

Not really. Here napisano is best understood as a passive participle describing a state or result:

• je napisano = is written

So the idea is not mainly someone wrote it in the past, but rather it is there in written form.

Compare:

• On je napisao poruku. = He wrote the message.
• Poruka je napisana. = The message is written / has been written.

In your sentence, sve je jasno napisano means everything is clearly written.

Because sve meaning everything is grammatically treated as neuter singular in Croatian.

So you get:

• sve je dobro
• sve je jasno
• sve je napisano

Even though the meaning is collective, the grammar is singular neuter.

That is why the participle is napisano, not napisani.

After nema = there is not / there are no, Croatian normally uses the genitive.

So:

• ima napomena = there are notes
• nema napomena = there are no notes

Here the full phrase is:

• novih napomena = of new notes / new notes in genitive plural

The adjective and noun both go into the genitive plural:

• novih
  • napomena

This is a very important pattern in Croatian:

• ima + genitive is common in existential meanings
• nema + genitive is especially common and something learners should get used to quickly

In school context, dnevnik usually does not mean a personal diary.

Here it means something like:

• class register
• grade book
• school record book
• sometimes class journal

So u dnevniku nema novih napomena means there are no new written remarks or notes in the school record.

A learner should be careful with dnevnik, because depending on context it can mean:

• a diary/journal
• a logbook
• a school register
• even a news program in some contexts

Napomena is a note, remark, or comment.

In school context, napomene often means official remarks written down by a teacher, for example about behavior, homework, or something that should be recorded.

So nema novih napomena suggests there are no newly added remarks in the class record.

It sounds a bit more formal and institutional than a casual English note.

Yes. Croatian allows a lot of word-order variation, as long as the relationships stay clear.

For example, these are all possible:

• U školi nam je obično lakše...
• Obično nam je u školi lakše...
• Nam je u školi obično lakše...

The original version sounds natural because it begins with the setting u školi, then gives the experiencer nam, then the frequency obično, and then the main comment lakše.

So the word order is flexible, but the original is smooth and idiomatic.