"She eats the apple."
Translation:Sie isst den Apfel.
For anyone who wishes there were pages with tips and notes for the lessons... there are!
You can usually find them by clicking the lightbulb icon before you start a lesson. If they are not available on your app, try the web version.
The accusative case is used when the article applies to the direct object of the sentence. So when you say, "She is eating the apple", the apple is the direct object and so the article (the) will be in the accusative case. I found this web page http://german.speak7.com/german_articles.htm and it REALLY helped me understand what's going on. It'll take just five or eight minutes to read!
You are asked here to translate "She eats the apple", It's "Sie" for She, "isst" for eats (because the conjugation of the verb Essen for He and She is "isst" and not esse, which is used for "Ich esse" - "I eat"), and then "den Apfel" for "the apple". It's not "Eine" because eine is the word "a / an" for feminine, and even not "der" because they explained in the hints that when there is a masculine noun in the accusative form, it should be changed to "den" instead of "der". Hope I was clear enough, because English is not my native language.
The apple is die apfel
No, it isn't.
"the apple" is der Apfel in the nominative case and den Apfel in the accusative case.
die apfel is never correct -- die is for feminine or plural nouns (but Apfel is masculine), and nouns are always capitalised in German.
In the plural "the apples" is die Äpfel -- with Ä and not A. (And still capitalised.)
We definitely need grammar explanations easily accessible within the app, please.
I agree, but there's no point telling other learners here in the sentence discussion. You would need to tell Duolingo that, and they don't read sentence discussions. (In fact, I don't know of any way to contact them.)