There are 3 types of Tanween :
1) FATHATAIN 2) KASRATAIN 3) DHAMMATAIN
This lesson is about KASRATAIN
KASRATAIN symbol appears as two kasrah symbols below a letter.
KASRATAIN sign consists of two components
(1) Kasrah that produces 'I' sound
(2) Second Kasrah is an unwritten letter Nun saakin, that produces 'N' sound.
Thus will produce 'IN' sound.
(More lessons uploaded soon InshaAllah)