I agree, "The boy eats cheese is incorrect". It should be "the boy eats the cheese" with the definite article.
it is not incorrect. As in Spanish -also a Latin language- the nouns can be put together with the definite article, without meaning it. For example: "il cibo" can mean "the food" as well as just "food"
I have Italian classes at school and I know for sure that in Italian food can be also articulated and mean the same.
Being a native Spanish speaker, el chico come queso and el chico se come el queso have totally different meanings (and sometimes the verbs change).
Except in Italian you can say "Ho il burro" and it doesn't mean you have THE butter, just butter. That's what's confusing, it's not clear when they mean "I have/eat THE noun" and when they mean "I have/eat noun" because the article in Italian is almost always there, in these past lessons at least.
The boy eats cheese. Correct English. It means the boy eats cheese as a generalised subject. The boy eats THE cheese means that the boy eats a specific (one off) piece of cheese and probably all of it.
We know how to differentiate that in English.
What we don't know is how to differentiate in Italian. "Il ragazzo mangia il formaggio" Can mean both "The boy eats cheese" and "The boy eats THE cheese"
How can you tell which one they mean?
Agreed. If "il" is included in the sentence, then why wouldn't it be included in the translation?
If you keep the mouse over "mangia", where duolingo corrects you, you are able to see a button with the text "conjugate". Pressing it will show you that in Italian verbs have a different form for each person and number, and also, which one you should use for the current case.
Io mangio = I eat
Lui mangia = He eats
Edit: As with the latest updates, the "conjugate" button doesn't seem to exist anymore.
I know the article inclusion happens more often in Italian than in English without affecting meaning. I have a question, though, about how to emphasize the article in Italian. For example we have this sentence which tells us of a boy who eats cheese. Fine and dandy. However, if i want to specify that the boy eats cheese to the exclusion of other foods, possibly fruit, that are on offer as opposed to general cases, in English i could say "the boy eats the cheese, the girl eats the fruit." How would this be expressed in Italian with the specifying articles?