German Accusative Case
After practicing and practicing, I still can't quite tell when a sentence uses the Accusative case and how to use "den" in the Accusative Case, any pointers?
In your head break the (simple) sentence you want to translate into "subject verb object". For example "I subject see verb the dog object." In German the object of the sentence is in the accusative case, so it would be "ich sehe den Hund" and not "ich sehe der Hund" because the masculine accusative definite article is den. An exception to this is with sein, in that case you use nominative on both sides "ich bin der Hund", not "ich bin den Hund" (this is different to English in the few places English marks accusative).
Another way to do it is to try replace the word in the sentence with he/she or him/her. If he or she sounds right in that position it's nominative, if him or her it's accusative (keeping in mind the sein exception I pointed out in the previous paragraph). "I see the dog" compared to "I see he" or "I see him", the second one is the correct one so dog should be accusative.
There is not too much to the Accusative luckily! The only genders affected are the masculine words. How it works is if the noun is masculine and directly affected it goes to den, or einen. See how Ich bin ein Mann is not accusative because the object, a man, is not affected by a verb. However saying Ich habe einen Hund ( I have a dog ) is accusative because the dog is being affected by the verb have. If you need this further explained I can help.