In short

Lesson 46 laid out the grid: one root, a set of moulds, each mould a verb with its own shape and its own slant of meaning. This lesson conjugates the first five of those moulds - II فَعَّلَ, III فاعَلَ, IV أَفْعَلَ, V تَفَعَّلَ, VI تَفاعَلَ - the five you meet most often on a page of modern Arabic. دَرَّسَ “he taught”, سافَرَ “he travelled”, أَرْسَلَ “he sent”, تَعَلَّمَ “he learned”, تَعاوَنَ “he cooperated”: one completely ordinary verb from each.

The good news is that you already know the endings. Every person marker you learned for the plain verb - ـْتُ، ـْنا، ـوا at the back in الماضي, and the أَـ نَـ تَـ يَـ prefixes in المُضارِع - is exactly the same here. What changes is only the stem they attach to. So this lesson is not five new paradigms; it is five new stems plus two small vowel rules, and once those click you can conjugate a derived verb you have never seen, from its headword alone.

The rule

1. New stems, old endings. دَرَّسْتُ is a new stem plus the same ـْتُ that gave you كَتَبْتُ; يُدَرِّسونَ is a new stem inside the same يـ … ـونَ frame that gave you يَكْتُبونَ. Nothing about the ماضي endings, the مُضارِع frame, the silent alif of ـوا or the dual is renegotiated by the derived forms. Build the stem and the conjugation is free.

2. Form II فَعَّلَ doubles the middle radical. That is the whole shape: take د-ر-س, put a shadda on the ر, and you have دَرَّسَ. The past is three fatḥas - دَرَّسَ - and the imperfect is يُدَرِّسُ. Because the shadda is the only difference between دَرَسَ (Form I, “he studied”) and دَرَّسَ (Form II, “he taught”), and because ordinary Arabic rarely prints the shadda, this pair is the classic reading trap of the whole system. Write the shadda yourself, always.

3. Forms III and IV: a long ā, and a hamza that does not survive. Form III فاعَلَ inserts a long ا after the first radical: س-ف-ر gives سافَرَ, ش-ه-د gives شاهَدَ. Form IV أَفْعَلَ bolts a هَمْزَةُ قَطْعٍ onto the front and puts a sukūn on the first radical: ر-س-ل gives أَرْسَلَ, ع-ل-ن gives أَعْلَنَ. That أَ is a genuine قَطْع hamza in the past - you hear it, you write the seat - but it vanishes in the imperfect: أَرْسَلَ becomes يُرْسِلُ, never *يُأَرْسِلُ. In the first person only one hamza survives the collision: أُرْسِلُ, “I send”, not *أُأَرْسِلُ. Of the five moulds here, Form IV is the only one that loses a letter between its two tenses.

4. The prefix vowel splits the five forms into two families. This is the single most useful fact in the lesson, and the one beginners get wrong first:

• Forms II, III and IV take a ḍamma on the imperfect prefix: يُدَرِّسُ، يُسافِرُ، يُرْسِلُ. Not يَـ - and in every person: أُدَرِّسُ، تُسافِرُ، نُرْسِلُ، يُشاهِدونَ.
• Forms V and VI take a fatḥa, exactly like the plain verb: يَتَعَلَّمُ، يَتَعاوَنُ، أَتَكَلَّمُ، نَتَبادَلُ.

Say it as one sentence: the middle three take ḍamma, the تَـ pair takes fatḥa. Lesson 48 will confirm the generalisation behind it: among the ten triliteral forms only II, III and IV take a ḍamma there in the active. (The four-letter verb يُتَرْجِمُ of lesson 48 joins them, and the passive of lesson 52 vowels every prefix with a ḍamma - neither is a counter-example you need yet.)

5. The vowel before the last radical splits them the same way. II, III and IV carry a kasra on the letter in front of the last one - يُدَرِّسُ، يُسافِرُ، يُرْسِلُ - while V and VI carry a fatḥa there: يَتَعَلَّمُ، يَتَعاوَنُ. So the two rules travel together and you learn one thing, not two: يُـ + kasra against يَـ + fatḥa. The kasra also matters for a reason you meet in lesson 52: يُدَرَّسُ, with a fatḥa in that slot, is not a mistake but a different word - the passive, “is taught”.

6. Forms V and VI are Forms II and III with a تَـ in front. V تَفَعَّلَ is the doubled middle radical of II with تَـ prefixed; VI تَفاعَلَ is the long ā of III with تَـ prefixed. That تَـ is part of the word, not a person marker, which produces two consequences:

• The V and VI past carries a fatḥa on every letter that has a vowel at all: تَعَلَّمَ، تَكَلَّمَ، تَعاوَنَ، تَبادَلَ. No kasra, no ḍamma, anywhere in the stem.
• The imperfect of “you” and “she” ends up with two تs, one from the pattern and one from the person: تَتَعَلَّمُ “you learn / she learns”, تَتَكَلَّمينَ “you (f.) speak”. They look odd and they are correct. Never delete one.

7. تَعَلَّمَ is “he learned”, not “you learned”. A تَـ at the front of an Arabic verb usually means “you” or “she” - but only in المُضارِع. الماضي has no person prefix at all, so the تَـ of تَعَلَّمَ، تَكَلَّمَ، تَعاوَنَ can only be the pattern. تَعَلَّمَ is the dictionary headword, “he learned”; “you learned” adds the ordinary ending at the back, تَعَلَّمْتَ.

8. The نون of الأَفْعال الخَمْسَة is the مَرْفوع marker - and a second نون is not. Five cells of the imperfect end in ن: تُدَرِّسينَ، تُدَرِّسانِ، يُدَرِّسانِ، تُدَرِّسونَ، يُدَرِّسونَ. Those are الأَفْعالُ الخَمْسَةُ of lesson 40, and their final ن is نونُ الرَّفْعِ - it is how they show المُضارِع المَرْفوع, exactly as the ḍamma of يُدَرِّسُ shows it. In a plain statement the ن must be there; after لَنْ or أَنْ or لَمْ it drops (لَنْ يُدَرِّسوا). Two more cells end in ن - تُدَرِّسْنَ and يُدَرِّسْنَ - but theirs is نونُ النِّسْوَةِ, the pronoun itself, and it never falls off, because those cells are مَبْنِيّ.

9. What the forms mean: a strong tendency, not a formula. Each mould has a job, and knowing it turns half your vocabulary into something you can reconstruct instead of memorise:

• II فَعَّلَ - makes a verb causative (عَلِمَ “knew” → عَلَّمَ “taught”, i.e. caused to know; دَرَسَ “studied” → دَرَّسَ “taught”), or intensifies it (كَسَرَ “broke” → كَسَّرَ “smashed to pieces”).
• III فاعَلَ - aims the action at another party: كَتَبَ “wrote” → كاتَبَ “wrote to someone”; قَبِلَ “accepted” → قابَلَ “met, interviewed”; دَرَسَ → دارَسَ “studied with”. Form III verbs are usually transitive, and where the mould’s own sense is live the object is that other party.
• IV أَفْعَلَ - causative again, often more bookish than II: عَلِمَ → أَعْلَمَ “informed”; خَرَجَ “went out” → أَخْرَجَ “took out, produced”.
• V تَفَعَّلَ - the reflexive or the result of II. عَلَّمَ “taught” → تَعَلَّمَ “learned” (taught himself); حَرَّكَ “moved something” → تَحَرَّكَ “moved, set off”.
• VI تَفاعَلَ - the reciprocal of III. كاتَبَ “wrote to” → تَكاتَبَ “wrote to each other”; قابَلَ “met” → تَقابَلَ “met one another”. A VI verb usually has a plural or dual subject.

10. Look it up anyway. Those tendencies are how the language got built, not a machine you can run in reverse. شاهَدَ is Form III but means plain “to watch”, with no second party in sight; سافَرَ is Form III with no Form I “travel” behind it; تَقَبَّلَ (V) is not the passive of قَبَّلَ (II) but “to receive, to accept graciously”. Use the pattern to remember a meaning you have read in a dictionary and to guess intelligently in a text - never to invent a verb. Most roots use only three or four of the ten forms, and which ones is a fact about the root.

11. Sound stems only, and only the two tenses. Every verb here conjugates like a sound triliteral: no hamza, no doubled radical, nothing inside the stem that shifts or drops. (تَعاوَنَ does carry a و in its root ع-و-ن, but the long ا of III and VI holds a weak middle radical in place as a consonant, so it behaves exactly like تَبادَلَ.) The roots that really do reshape these patterns are lessons 49-51. Also deliberately absent: the مَصْدَر of each form (lesson 54), the participles مُدَرِّس and مُتَعَلِّم (lesson 53), the passive يُدَرَّسُ (lesson 52), and Forms VII-X (lesson 48).

Forms & patterns

Form II in full. دَرَّسَ / يُدَرِّسُ (root د-ر-س, “to teach”), all thirteen persons in الماضي and in المُضارِع المَرْفوع:

The five cells تُدَرِّسينَ، تُدَرِّسانِ، يُدَرِّسانِ، تُدَرِّسونَ، يُدَرِّسونَ are الأَفْعالُ الخَمْسَةُ, and their final ن is نونُ الرَّفْعِ, the marker of المَرْفوع. تُدَرِّسْنَ and يُدَرِّسْنَ end in ن too, but theirs is نونُ النِّسْوَةِ, a pronoun that never drops.

Forms III to VI, five slots each (أَنا، هُوَ، هِيَ، نَحْنُ، هُمْ). The eight cells not shown

• أَنْتَ، أَنْتِ، أَنْتُمْ، أَنْتُنَّ، هُنَّ and the three duals - take exactly the endings of the Form II table above, on the same stem:

Two cells there deserve a second look. أَعْلَنَّا and تَعاوَنَّا carry a shadda because the last radical of ع-ل-ن and ع-و-ن is itself a ن and merges with the ن of the ending ـْنا. Nothing to do with the derived forms - Form I سَكَنَ does the same: سَكَنَّا.

The five moulds side by side. This is the table to memorise:

Meaning read off the root. A dash means the root does not use that form in ordinary MSA:

Examples

Common mistakes

• يَدَرِّسُ -> يُدَرِّسُ - Forms II, III and IV vowel their imperfect prefix with a ḍamma. A fatḥa there belongs to Form I and to Forms V-VI.
• يُتَعَلَّمُ -> يَتَعَلَّمُ - the mirror image of the rule above: the تَـ forms keep the fatḥa prefix. Fix the prefix and the stem vowel usually follows.
• يُدَرَّسُ for “he teaches” -> يُدَرِّسُ - the vowel before the last radical is a kasra. With a fatḥa the word is real but passive, “is taught” (lesson 52).
• دَرَّسْتُ اللُّغَةَ العَرَبِيَّةَ سَنَتَيْنِ meaning “I studied Arabic for two years” -> دَرَسْتُ اللُّغَةَ العَرَبِيَّةَ سَنَتَيْنِ - دَرَسَ (I) is “study”, دَرَّسَ (II) is “teach”. One shadda, opposite sides of the classroom - and unvowelled text prints neither.
• يُأَرْسِلُ -> يُرْسِلُ - the هَمْزَةُ القَطْعِ of أَرْسَلَ lives only in the past. Every imperfect prefix swallows it.
• أُأَرْسِلُ -> أُرْسِلُ - same rule in the first person: one hamza, not two. Compare أُعْلِنُ from أَعْلَنَ.
• تَعَلَّمَ العَرَبِيَّةَ meaning “you learned Arabic” -> تَعَلَّمْتَ العَرَبِيَّةَ - in الماضي there are no person prefixes at all, so the تَـ of تَعَلَّمَ is the pattern. The headword means “he learned”.
• تَعَلِّمْتُ -> تَعَلَّمْتُ - the Form V past is fatḥa throughout; there is no kasra anywhere in تَفَعَّلَ.
• أَتَعَلَّمُ الطُّلّابَ العَرَبِيَّةَ -> أُعَلِّمُ الطُّلّابَ العَرَبِيَّةَ - V تَعَلَّمَ is what you do to yourself, “learn”. “Teach” is II عَلَّمَ.
• هُمْ يُدَرِّسوا في المَدْرَسَةِ -> هُمْ يُدَرِّسونَ في المَدْرَسَةِ - a plain statement needs المُضارِع المَرْفوع, whose marker in الأَفْعال الخَمْسَة is the ن. The bare يُدَرِّسوا appears only after a particle that puts the verb in النَّصْب or الجَزْم - لَنْ، أَنْ، لَمْ and the like.

Tips

• Learn every derived verb as a pair, headword plus imperfect: دَرَّسَ / يُدَرِّسُ، أَرْسَلَ / يُرْسِلُ، تَعَلَّمَ / يَتَعَلَّمُ. One glance at the pair tells you the form, the prefix vowel and the stem vowel at once.
• Chant the two families until they are reflexes, not decisions: يُدَرِّسُ، يُسافِرُ، يُرْسِلُ in one breath, then يَتَعَلَّمُ، يَتَعاوَنُ in the next. Three ḍammas, then two fatḥas.
• Learn V next to II and VI next to III, never as a flat list of five. عَلَّمَ / تَعَلَّمَ and كاتَبَ / تَكاتَبَ are two pairs, and the تَـ is what “turns the action back” in each.
• Say the pattern name out loud after the verb, as you did in lesson 22: سافَرَ فاعَلَ، تَعاوَنَ تَفاعَلَ. Naming the mould is what makes you spot it in the next text.
• Write the shadda by hand every single time. دَرَسَ / دَرَّسَ، عَلِمَ / عَلَّمَ - the pairs that lose their difference in unvowelled print are the ones worth over-writing now.
• When you meet an unknown verb, strip it to the root and ask which of the five moulds it fits. That plus the context usually carries the sentence, and it always tells you which entry to open.
• Ignore for now: the مَصْدَر shapes (lesson 54), the participles (lesson 53), the passive (lesson 52), and any root whose hamza, و، ي or doubled radical actually reshapes the stem (lessons 49-51).