ما هي اول مهارة يجب ان يتقنها طالب المرحلة الابتدائية؟

I'm not sure which level exactly you mean among the phase you mentioned..But if it was the first grade so I believe the first skill that the student should master properly is reading which by itself can not be apart from the writing skill. This is if we are talking about the scientific level.. on the behavior level, I think the first skill he should learn is the team work and the sense of sharing. 

القراءة و الكتابة والانشاء

التعاون