Boat letters (ب - ت - ث)

• All have dots either one two or three

• Hook letters (ج - ح - خ)

• Two have dots, one does not

• Seated letters (د - ذ - ر - ز)

• Two have dots, to have not

• Three humps (س - ش)

• One has three dots, one has none

• Oval letters (ص - ض - ط - ظ)

• Each pair has one with a dot, one without