Breakdown of Eles ouvem o professor na aula.
o professor
the teacher (m)
eles
they (m)
na
in the / on the / at the (f.sg)
a aula
the class
Questions & Answers about Eles ouvem o professor na aula.
In English we say "listen to the teacher", so why is there no word for "to" after ouvem?
In Portuguese, the verb ouvir connects directly to the person or thing you are listening to. You don't need a preposition like "to" after it. You just put the noun right after the verb, as in ouvem o professor.
I thought ouvir meant "to hear". Shouldn't we use escutar for "to listen"?
You are right that escutar specifically means "to listen" (paying attention), while ouvir generally means "to hear" (the physical sense). However, in everyday Portuguese, people very often use ouvir to mean "listen to" as well, especially when talking about teachers, music, or the radio.
Why is it na aula instead of just em aula for "in class"?
Portuguese usually requires a definite article (the words for "the") before a noun, even in phrases where English drops it. Instead of just saying "in class", Portuguese says "in the class". You combine the preposition em (in) with the feminine article a (the) to make the contraction na.