Know who is Mukallaf 

Chapter#2 شُرُوط الصلاّة وأرْكَانُهَا Pre-Conditions (Shuroot) and Obligatory Elements (Arkaan) of Salaat

 Know who is Mukallaf
 Understand Shuroot and Furood of Salaat
 Differentiate between Shuroot and Arkaan