Durante a aula, ela abre o caderno e escreve com a caneta azul.

Durante means during.

So Durante a aula = During class / During the lesson.

The a before aula is the feminine singular definite article, meaning the. In Portuguese, articles are used more often than in English, so a aula is very natural here.

• durante = during
• a aula = the class / the lesson

So literally, it is During the class.

The comma separates the introductory time phrase from the main clause.

• Durante a aula, = introductory phrase telling us when
• ela abre o caderno e escreve com a caneta azul = main action

This is similar to English writing:

• During class, she opens her notebook...

The comma is very natural here, though punctuation can sometimes vary.

That is true: Portuguese often drops subject pronouns when the verb already makes the subject clear.

So you could also say:

• Durante a aula, abre o caderno e escreve com a caneta azul.

However, ela is included here for clarity, emphasis, or simply because the speaker wants to mention the subject explicitly.

Both are possible, but ela makes it very clear that she is the one doing the actions.

Abre is the 3rd person singular present tense of abrir (to open).

Conjugation:

• eu abro = I open
• você/ele/ela abre = you/he/she open(s)

So here:

• ela abre = she opens

It is the simple present, but in Portuguese the simple present can often cover meanings that English might express with either:

• she opens
• she is opening

Depending on context, this sentence could describe:

• a habitual action: During class, she opens her notebook and writes with the blue pen
• a scene happening now: During class, she opens her notebook and is writing with the blue pen

Portuguese often relies on context for that distinction.

Caderno usually means a notebook in the paper sense: something with pages used for writing.

It does not mean a laptop computer.

So:

• caderno = notebook / exercise book
• computador / notebook in Brazilian Portuguese can refer to a laptop, but caderno does not

In this sentence, o caderno clearly means a paper notebook.

Portuguese often uses definite articles where English might not.

So o caderno literally means the notebook, but in context it may sound natural in English as:

• her notebook
• the notebook
• just her notebook depending on the situation

Portuguese frequently uses the even when English might prefer a possessive or no article at all.

Portuguese does not always use a possessive where English does.

Instead of saying her notebook, Portuguese may simply say:

• o caderno

If the owner is obvious from context, that is enough.

You could say:

• o caderno dela = her notebook
• seu caderno = her notebook / your notebook (depending on context)

But in many everyday sentences, just o caderno sounds perfectly natural.

It means writes with the blue pen.

Breakdown:

• escreve = writes
• com = with
• a caneta azul = the blue pen

So the phrase shows the instrument used for writing.

Com is the normal Portuguese preposition for with when talking about the instrument used to do something.

Examples:

• escrever com uma caneta = to write with a pen
• cortar com uma faca = to cut with a knife
• pintar com um pincel = to paint with a brush

So escreve com a caneta azul is the standard way to say she writes with the blue pen.

In Portuguese, adjectives usually come after the noun.

So:

• caneta azul = blue pen
• carro preto = black car
• casa grande = big house

That is why azul comes after caneta.

In the singular, azul stays the same for masculine and feminine:

• o caderno azul = the blue notebook
• a caneta azul = the blue pen

In the plural, it changes:

• os cadernos azuis
• as canetas azuis

So in this sentence, azul does not change even though caneta is feminine.

Again, Portuguese commonly uses the definite article.

So a caneta azul literally means the blue pen.

Depending on context, English might translate this as:

• the blue pen
• a blue pen
• her blue pen

Portuguese often leaves that choice to context more than English does.

Naturally, it goes most directly with escreve.

So the sentence is understood as:

• She opens the notebook
• and writes with the blue pen

Grammatically, the phrase comes after both verbs, but semantically it matches escreve much more naturally. We normally do not interpret it as she opens the notebook with the blue pen.

E means and.

It links the two actions:

• abre o caderno = opens the notebook
• escreve com a caneta azul = writes with the blue pen

So the sentence shows a sequence of related actions.

Yes, if you specifically want to emphasize an action in progress.

For example:

• Durante a aula, ela está abrindo o caderno e está escrevendo com a caneta azul.

But that sounds more marked and less natural for a simple neutral description.

The original sentence with the simple present is more natural for:

• habitual actions
• general description
• narrative style

Aula can mean class, lesson, or lecture, depending on context.

In this sentence, the most natural English choices are:

• During class
• During the lesson

So Durante a aula refers to the period when the class is happening.

Yes, it is completely natural.

It sounds like a normal descriptive sentence in Brazilian Portuguese:

• Durante a aula, ela abre o caderno e escreve com a caneta azul.

It is simple, grammatical, and very typical in structure and vocabulary for a learner example.