In this post, I explain the difference between 2 verb forms: form II (فعَّلَ) and form V (تفعَّلَ). Form II is always transitive, i.e. it must take an object at all times, so the sentence in which a form II verb is used must have a subject and an object, e.g.
كسّر الولد الزجاج.
“The boy broke the glass.”
علّمني أبي القرآن.
“My father taught me the Qur’an.”
Form V is always intransitive, i.e. it never takes an object, so the sentence in which a form V verb is used has only a subject, e.g.
تكسّر الزجاج.
“The glass broke.”
تعلّمت القرآن.
“I learned the Qur’an.”
Form V verbs have a range of meanings implied in them; some verbs imply that the action is done by the subject, e.g.
تعلّم (learned) =
تكلّم = (spoke)
Some verbs imply that the action is spontaneous, e.g.
تكسّر = (broke)
تطوّر = (developed/evolved)
Some verbs imply that the subject is irrelevant or unknown, and in this case we translate it into passive in English, e.g.
تشرّف = (was honored)
تعزّز = (was strengthened)

