Na aula, eu leio o texto em voz alta.

In Portuguese, certain prepositions combine (contract) with the definite article:

• em + a = na
• em + o = no

So:

• em a aula → na aula (in the class / in class)
• em o carro → no carro (in the car)

Saying em a aula is grammatically wrong; native speakers always use the contracted form na aula.

Na aula can mean both, depending on context:

• Location – in the class / in the classroom (while you are physically there)
• Time/situation – during class / in the lesson (during that part of the day)

If you specifically want “in the classroom (room)”, you can also say:

• na sala de aula – literally “in the classroom”

In European Portuguese, a aula is the normal word for a class/lesson.

• a aula = a lesson, a class session
• a turma = the group of students (the class as a group)
• a classe = mainly “social class” (e.g. working class, middle class), or sometimes a school year level

So for “in class”, you should say na aula, not na classe, in Portugal.

No, it isn’t strictly necessary, but it is common and stylistically natural.

Both are correct:

• Na aula, eu leio o texto em voz alta.
• Na aula eu leio o texto em voz alta.

When you move a time/place expression to the beginning, Portuguese often uses a comma, especially in writing, but many speakers omit it in short sentences.

You can omit eu:

• Na aula, leio o texto em voz alta.

Portuguese is a “null-subject” language: the verb ending (leio) already shows the subject (I).

Including eu usually adds a bit of emphasis or contrast:

• Na aula, eu leio o texto em voz alta.
  → “In class, I read the text aloud (not someone else).”

In a neutral context, both versions are fine.

Ler (to read) is irregular in the present tense. The main forms are:

• eu leio – I read
• tu lês – you read (singular, informal)
• ele / ela lê – he / she reads
• nós lemos – we read
• vocês leem – you read (plural)
• eles / elas leem – they read

The -ei- in leio comes from the verb’s irregular pattern. You just have to memorise it; it doesn’t follow the regular -er endings exactly.

Portuguese uses definite articles (o, a, os, as) much more than English.

Here:

• o texto = the text (a specific text everyone knows about, for example the one in the book or on the page)

If you said just leio texto, it would sound incomplete or wrong. A noun in Portuguese almost always needs an article, a determiner, or something before it unless there’s a special reason not to.

Yes, but the meaning changes:

• eu leio o texto – I read the text (a specific, known text)
• eu leio um texto – I read a text (some text, not specified which one)

In a classroom context, o texto usually refers to the particular text in the book or exercise that everyone is looking at.

em voz alta literally means “in high voice”, and it’s the standard idiomatic way to say aloud / out loud.

• ler em voz alta – to read aloud
• falar em voz alta – to speak loudly / out loud

Just saying alto after the verb (leio o texto alto) is not idiomatic for “aloud”; it would more likely be understood as “I read the text loudly” in a more physical, noisy sense, and even then it doesn’t sound natural.

So for “aloud / out loud”, you should use em voz alta.

In Portuguese, adjectives agree in gender and number with the noun they describe.

• a voz = voice → feminine singular
• alto / alta = high, loud

So:

• voz alta – loud/high voice (feminine, to match voz)
• voz baixa – low/quiet voice (also feminine)

If the noun were masculine, the adjective would be masculine, e.g.:

• som alto – loud sound (masculine)

Yes. The most natural positions are:

• Na aula, eu leio o texto em voz alta.
• Na aula, eu leio em voz alta o texto.

Both are grammatical. The first is more common and flows more naturally.

You could also drop the eu:

• Na aula, leio o texto em voz alta.

Avoid splitting em voz alta apart; it works as a unit.

In European Portuguese:

• Eu leio o texto em voz alta.
  – Can mean a present habit (In class, I (usually) read the text aloud)
  – Or a current action (Right now, I’m reading the text aloud), depending on context.

To be very clear that it’s happening right now, Europeans often use the progressive:

• Eu estou a ler o texto em voz alta. – I am reading the text aloud (right now).

So both are correct; estou a ler just makes the “right now” meaning explicit.

Put não before the verb:

• Na aula, eu não leio o texto em voz alta.
  → In class, I do not read the text aloud.

If you omit eu:

• Na aula, não leio o texto em voz alta.

In everyday European Portuguese, you usually keep the word order and use intonation (your voice rising at the end):

• Na aula, eu leio o texto em voz alta?
  – “In class, do I read the text aloud?” / “Do I read the text aloud in class?”

For written or more formal style, you can invert subject and verb:

• Na aula, leio eu o texto em voz alta?

Both are grammatically correct, but the first (no inversion, just question intonation) is more common in speech.