It depends on the verb that is being used, and for adverbials and prepositional objects, on the preposition being used. So you learn the full verb pattern ("jemandem (Dat) etwas (Akk) geben", "sich mit etwas (Dat) abfinden") instead of just "geben" and "abfinden". You also learn the preposition together with the case, see e.g. http://www.mein-deutschbuch.de/lernen.php?menu_id=82 http://www.mein-deutschbuch.de/lernen.php?menu_id=83 http://www.mein-deutschbuch.de/lernen.php?menu_id=84 http://www.mein-deutschbuch.de/lernen.php?menu_id=85 for tables. Some prepositions can take both dative and accusative ("Wechselpräpositionen"), dative for a location, and accusative for a direction.