U školskom dnevniku je upisano da sutra imamo kratki test iz hrvatskog.

It means in the school register / in the class record book.

Why that form:

• u = in
• after u (when it means location), Croatian normally uses the locative
• so:
  • školski dnevnik = the school register
  • u školskom dnevniku = in the school register

Both words change because the adjective must agree with the noun:

• školski → školskom
• dnevnik → dnevniku

Also, dnevnik here does not mean a personal diary. In a school context, it means the official class record book/register.

Because Croatian nouns change form depending on their role in the sentence.

Here the phrase comes after u meaning in, so Croatian uses the locative case:

• base form: školski dnevnik
• locative: školskom dnevniku

The adjective and noun must match in:

• gender
• number
• case

So:

• masculine singular nominative: školski dnevnik
• masculine singular locative: školskom dnevniku

Je upisano is an impersonal passive-style expression meaning something like:

• it is written down
• it has been entered
• it is recorded

This is very common in Croatian when the doer is unimportant or unknown.

Breakdown:

• je = is / has been
• upisano = written down, entered, recorded

The form upisano is neuter singular, which is often used in Croatian in impersonal constructions, especially when what follows is a whole clause:

• je upisano da... = it is recorded that...

English often uses a dummy subject it, and Croatian often uses this kind of neuter impersonal form instead.

Because this is not describing a specific masculine or feminine noun. It is functioning impersonally.

Croatian often uses neuter singular in expressions like:

• rečeno je da... = it was said that...
• poznato je da... = it is known that...
• upisano je da... = it is recorded that...

So upisano is not agreeing with dnevnik here. It is part of an impersonal structure meaning roughly it is recorded that...

Da introduces a subordinate clause. Here it means that.

So:

• je upisano da... = it is recorded that...

The clause after da is:

• sutra imamo kratki test iz hrvatskog

So da links the two parts:

• main clause: U školskom dnevniku je upisano
• subordinate clause: da sutra imamo kratki test iz hrvatskog

Because in Croatian, the present tense of an imperfective verb is often used for the future when:

• there is a clear time word such as sutra (tomorrow)
• the event is planned or scheduled

So:

• sutra imamo test = tomorrow we have a test
• this naturally refers to the future

This is similar to English:

• Tomorrow we have a test not necessarily
• Tomorrow we will have a test

Both languages can use a present form for scheduled future events.

Because Croatian usually leaves out subject pronouns when they are not needed.

The ending -mo in imamo already tells you the subject is we:

• imam = I have
• imaš = you have
• ima = he/she/it has
• imamo = we have

So mi imamo is possible, but usually unnecessary unless you want emphasis:

• Mi imamo test, a oni nemaju. = We have a test, but they don’t.

Because kratki test is the direct object of imamo.

The verb imati takes an object in the accusative:

• imamo što? = we have what?
• kratki test

For masculine animate nouns, accusative often changes more visibly, but test is masculine inanimate, so nominative and accusative look the same:

• nominative: kratki test
• accusative: kratki test

So the form is correct even though it looks like the dictionary form.

Iz hrvatskog means in Croatian / on Croatian / from Croatian in the sense of a school subject.

After iz, Croatian uses the genitive:

• iz + genitive

So:

• base form: hrvatski
• genitive form: hrvatskog

In school language, Croatian often omits the noun jezik:

• iz hrvatskog (jezika) = from/of the Croatian language subject

This kind of shortening is very common with school subjects:

• test iz matematike
• ispit iz fizike
• zadaća iz engleskog

So iz hrvatskog is perfectly natural.

Yes. Croatian word order is more flexible than English word order.

The given sentence is natural:

• U školskom dnevniku je upisano da sutra imamo kratki test iz hrvatskog.

But you could also hear variations such as:

• Je upisano u školskom dnevniku da sutra imamo kratki test iz hrvatskog.
• Da sutra imamo kratki test iz hrvatskog, upisano je u školskom dnevniku.

However, not all versions sound equally natural in everyday speech. The original order is good because it:

• starts with the location/source of information
• then gives the reporting phrase
• then gives the content

So yes, word order can change, but the original is a very normal and clear choice.

Yes, absolutely.

• U školskom dnevniku piše da... = It says in the school register that...
• U školskom dnevniku je upisano da... = It is written/recorded in the school register that...

The difference is mainly stylistic:

• piše sounds a bit more everyday and direct
• je upisano sounds a bit more formal or administrative

Both are correct and natural.

Not exactly.

• kratki test = a short test, usually something brief
• test = test/quiz
• ispit = exam, usually more formal or important

So in a school context:

• kratki test often suggests a small classroom test or quiz
• ispit sounds bigger and more serious

That is why kratki test fits this sentence well.