01Start with the thing, then its connection
Read from right to left. In these examples, the first noun names the thing and the second tells you whose it is. There is no separate word for English “of” or the possessive ’s.
كِتَاب = book; الطَّالِب = the student. Start with the book.
بَاب = door; الْغُرْفَة = the room. A connection need not mean a person owns something.
02Give each noun its job
The first noun is the muḍāf; the second is the muḍāf ilayh. In this ordinary possessive pattern, the first has neither الْـ nor tanwin. The second is genitive (jarr). For the ordinary singular nouns shown here, that means a kasra ending.
The first noun’s case depends on its role in the sentence. It does not automatically become genitive because it is in an idafa. Compare the examples below.
كِتَابُ is the topic, so it is nominative here. جَدِيدٌ = new.
فِي makes كِتَابِ genitive; الطَّالِبِ remains genitive as the second noun.
03“The” belongs to the whole phrase
Compare the second nouns. With الْـ, the student is definite and the whole phrase is definite. With an indefinite student, the phrase stays indefinite. Do not put الْـ on the first noun to make this possessive phrase definite.
A particular student is identified.
طَالِبٍ is indefinite. Its double kasra is tanwin; the first noun still has no tanwin.
04Keep the first step small
Practise two ordinary singular nouns before adding adjectives, pronouns or a longer chain. Other idafa patterns and other noun types require more detail.
Cover the translations. Locate the thing first, then the noun that identifies its connection. Finally, check the second noun’s ending. Case endings are shown for learning; a final short case ending is often omitted when pausing.