A professora fez-nos folhear o livro devagar e não rabiscar nas margens.

In European Portuguese, unstressed object pronouns such as me, te, se, nos, vos, o, a, lhes often come after the verb in an affirmative main clause. That is called enclisis.

So:

• fez-nos = made us

The hyphen is the normal written way to attach the pronoun to the verb.

If something pulls the pronoun forward, then it goes before the verb instead. For example:

• A professora não nos fez folhear o livro.
• Quem nos fez folhear o livro?

In everyday Brazilian Portuguese, nos fez is much more common even without one of those triggers.

This is the very common fazer + someone + infinitive pattern, which expresses causing or making someone do something.

So:

• fazer alguém folhear o livro
• to make someone leaf through the book

Here:

• fez = made
• nos = us
• folhear = the action we were made to do

It works much like English make + object + base verb:

• The teacher made us leaf through the book.

Portuguese also uses this pattern with other verbs such as:

• deixar = let, allow
• mandar = order, tell someone to do something

Because after causative fazer, the action being caused is normally expressed with the infinitive.

So:

• fez-nos folhear
• fez-nos ... não rabiscar

This is quite close to English:

• made us leaf through
• not made us leafed through

The second action is also in the infinitive because it depends on the same fez-nos. Portuguese is effectively saying:

• The teacher made us [folhear the book slowly] and [not scribble in the margins].

Not quite.

Folhear means something like:

• to leaf through
• to flip through
• to browse through pages

It focuses on turning or looking through pages, not on fully reading the text.

By contrast:

• ler = to read

So if the teacher wanted the students to actually read the book, ler would be more direct.
With folhear, the idea is more like examining or going through the book page by page.

Rabiscar means:

• to scribble
• to scrawl
• to doodle carelessly

It has a slightly messy or careless feel. It is not the neutral verb escrever.

So:

• escrever nas margens = write in the margins
• rabiscar nas margens = scribble in the margins

In this sentence, rabiscar suggests unwanted marks in the book, which is exactly the kind of thing a teacher would forbid.

Because both infinitives are governed by the same verb phrase, so Portuguese avoids repeating it unnecessarily.

Structure:

• fez-nos folhear o livro devagar
• e não rabiscar nas margens

This is like English:

• The teacher made us leaf through the book slowly and not scribble in the margins.

Repeating fez-nos would be possible in theory, but it would sound heavier and less natural:

• A professora fez-nos folhear o livro devagar e fez-nos não rabiscar nas margens.

The version with one fez-nos is smoother and more idiomatic.

Yes. Portuguese can absolutely negate an infinitive by putting não directly before it.

Examples:

• não fumar = not to smoke / no smoking
• não entrar = not to enter / do not enter
• não tocar = not to touch

So não rabiscar is completely normal and means not to scribble or, in this sentence, simply not scribble.

Here devagar most naturally modifies folhear.

So the idea is:

• leaf through the book slowly

In this sentence, it does not naturally apply to não rabiscar.

Its position is normal and natural:

• fez-nos folhear o livro devagar

Portuguese adverbs are somewhat flexible, but not every position sounds equally natural. This sentence is a very standard way to place devagar.

You could also hear or use:

• fez-nos folhear devagar o livro — possible, but less neutral
• fez-nos folhear o livro lentamente — more formal because of lentamente

Nas is a contraction of:

• em + as = nas

So:

• nas margens = in the margins

This happens very often in Portuguese:

• no = em + o
• na = em + a
• nos = em + os
• nas = em + as

Margens is plural, so nas has to be plural too.

In book-related contexts, Portuguese commonly uses the plural:

• escrever nas margens
• rabiscar nas margens

Fez is the preterite form of fazer, third person singular.

So:

• A professora fez... = The teacher made...

The preterite is used for a completed action in the past.

Compare:

• faz = makes
• fez = made
• fazia = used to make / was making

It is also an irregular form, so learners simply have to get used to:

• fazer → fez

Yes, the sentence has a distinctly European Portuguese feel, especially because of fez-nos.

In everyday Brazilian Portuguese, a very common version would be:

• A professora nos fez folhear o livro devagar e não rabiscar nas margens.

So the biggest difference is usually the pronoun placement:

• European Portuguese: fez-nos
• Brazilian Portuguese: nos fez

The rest of the sentence is understandable in both varieties. In casual Brazilian speech, you might also hear more rephrased versions, such as using a gente or a different verb like mandar, depending on context.