Al-Jazeera offers a grammar test. There are a couple of pitfalls. So, reason enough to take a look at the most important Arabic grammar topics.
Adjectives in Egyptian Arabic can be tricky. Sometimes you need to form the plural. An overview of the most common plural patterns of Egyptian adjectives.
Many websites offer free Arabic lessons. Two of the best are Playaling and material of the Defense Language Institute.
The Arabic broken plural has the effect that scholars still debate how to properly classify the several branches of Semitic languages.
What are the best Arabic grammar books (nahw and sarf) for beginners, intermediate and advanced students? Some recommendations (in English, German, Arabic).
Episode #8 of my series "9273 roots": 20 questions for the man who coded the best desktop-app for Lane's Arabic-English Lexicon: Graeme Andrews.
The plural of Mustafa in Arabic is difficult - because there is a weak letter involved. How do you form masculine human plurals with a possessive pronoun?
Arabic knows two plural forms depending on the number of things: plural for small numbers (jama al-qilla) and big numbers (jama al-kathra).