The ten verb forms
Arabic · GCSE · The School
One root, ten shapes
From ع-ل-م: Form I عَلِمَ (he knew), Form II عَلَّمَ (he taught — doubling the middle letter makes it causative), Form IV أَعْلَمَ (he informed), Form V تَعَلَّمَ (he learned — for himself), Form X اِسْتَعْلَمَ (he sought information). The root gives the field of meaning; the form gives the ANGLE.
The shifts are predictable
Form II usually intensifies or makes causative. Form III often means doing something WITH someone (قاتَلَ, he fought with). Form V is often Form II turned back on the doer. Form VII and VIII are frequently passive or reflexive. Form X very often means "to seek or ask for" — اِسْتَغْفَرَ, to seek forgiveness.
Reading with forms in mind
When you meet an unfamiliar verb, find the root and identify the form; you can then often guess the meaning before checking. نَسْتَعينُ in Al-Fatihah is Form X of ع-و-ن (help) — "we SEEK help", which is exactly what Form X does. Grammar here is not academic; it is the meaning itself.
From ع-ل-م, knowing. Form I عَلِمَ — he knew. Form II عَلَّمَ — he TAUGHT (doubling the middle letter makes it causative). Form IV أَعْلَمَ — he informed. Form V تَعَلَّمَ — he LEARNED (reflexive of teaching). Form X اِسْتَعْلَمَ — he enquired. One root, five verbs, each with its own past and present. The forms multiply vocabulary; they are not tenses.