Just looked through all the words in Portuguese 1:
These are all the words without an article (o/a). The number = level
Also there are some words, which have an indefinite article only (um/uma). These words are missing with their definite article.
Or even words like “dia” or “noite”, which aren’t explained directly, because they come in pairs with “bom” or “boa”
Is there a way to give a little introduction for a course? Maybe about the use of articles (definite/indefinite)? If so, then one only would need to define one article (either definite or indefinite) and it would be clear to learners.
So if a word has the indefinite article “uma” the definite article is (at least most of the time) automatically “a”