Learn Arabic (Modern Standard): رسب في المقرر لأنه لم يدرس جيدا. - He failed the course because he did not study well.

In Arabic, the verb رسب (to fail or flunk) is intransitive, so it cannot take a direct object on its own. You must use the preposition في (in) to indicate what someone failed. Literally, the sentence says "He failed in the course."

How does المقرر differ from other words for "course" or "class"?

المقرر specifically refers to a syllabus, curriculum, or an academic module. It comes from a root meaning "to decide or establish," so it refers to a set curriculum. If you were talking about a short training course, you would use دورة, and for a physical classroom or grade level, you would use صف.

What happens to the ending of the verb يدرس when it follows لم?

The negative particle لم (did not) forces the present-tense verb that follows it into the jussive mood. For a regular verb like يدرس, this means it loses its final vowel and ends with a sukoon (a vowelless pause). Even though the verb structure is present-tense, لم changes its meaning to the past tense.

Why does جيدا have the "-an" ending here?

The word جيدا (good) is an adjective being used here as an adverb (well). In Arabic, you can often turn an adjective into an adverb by putting it in the accusative case, which is marked by the double-fatha ending (ـًا).