So I've been learning German recently and one of the resources I've used to learn is the Language Transfer course. One extremely useful trick I learned from this course is how to derive German definite articles from their corresponding pronouns.
The idea is that for each case (e.g. nominative, accusative, or dative) you can derive the correct definite article from the corresponding pronoun by replacing the beginning of the pronoun with "d-" (and maybe squinting a little bit).
For example, in the nominative case (for the subject of a sentence), the masculine/feminine/neutral/plural subject pronouns are er/sie/es/sie. So if you replace the beginning of each word with "d-" (and squint a little) you get the corresponding nominative definite articles: der/die/das/die. Or in table form:
| Gender | Object pronoun | Definite article |
|---|---|---|
| Masculine | er | der |
| Feminine | sie | die |
| Neutral | es | das |
| Plural | sie | die |
Similarly, in the accusative case (for the object of a sentence), the masculine/feminine/neutral/plural object pronouns are ihn/sie/es/sie. Following the same pattern, the corresponding accusative definite articles are den/die/das/die:
| Gender | Object pronoun | Definite article |
|---|---|---|
| Masculine | ihn | den |
| Feminine | sie | die |
| Neutral | es | das |
| Plural | sie | die |
In the dative case, there is one wrinkle. The masculine/feminine/neutral dative pronouns are ihm/ihr/ihm and the corresponding definite articles are dem/der/dem (so far, so good). However, the plural object pronoun is "ihnen", so how do you translate to the corresponding definite article?
Well, you split "ihnen" into "ihn-" + "-en", the "ihn-" turns into the corresponding plural dative definite article ("den") and the "-en" gets tacked onto the noun that the article modifies. For example, when you say "the children" in the dative case in German it becomes "den Kindern"; the "n" at the end of "Kindern" is (conceptually) derived from the "-en" of "ihnen" tacked onto the end of "Kinder" (children).
| Gender | Object pronoun | Definite article |
|---|---|---|
| Masculine | ihm | dem |
| Feminine | ihr | der |
| Neutral | ihm | dem |
| Plural | ihnen | den + -n |
In fact, this pattern holds to some extent for indefinite and negative articles, too (albeit not as strongly), where you replace the beginning of the word with "ein-" or "kein-".a
For example, for nominative pronouns/articles, the pattern only holds very weakly (you have to squint pretty heavily):
| Gender | Object pronoun | Indefinite article | Negative article |
|---|---|---|---|
| Masculine | er | ein | kein |
| Feminine | sie | eine | keine |
| Neutral | es | ein | kein |
| Plural | sie | N/A | keine |
For accusative pronouns/articles the pattern gets a little bit stronger:
| Gender | Object pronoun | Indefinite article | Negative article |
|---|---|---|---|
| Masculine | ihn | einen | keinen |
| Feminine | sie | eine | keine |
| Neutral | es | ein | kein |
| Plural | sie | N/A | keine |
… and for the dative case the pattern goes back to being pretty strong:
| Gender | Object pronoun | Indefinite article | Negative article |
|---|---|---|---|
| Masculine | ihm | einem | keinem |
| Feminine | ihr | einer | keiner |
| Neutral | ihm | einem | keinem |
| Plural | ihnen | N/A | keinen + -n |
Remembering this trick makes it much easier to keep track of what all of the definite/indefinite/negative articles are supposed to be, because if you can remember the corresponding pronouns you can in most cases derive the correct article just by replacing the pronoun with the correct prefix (either "d-", "ein-" or "kein-"). There are a few exceptions (especially for the nominative cases for indefinite/negative articles), but it's easier to memorize those exceptions than to memorize all of the cases.