Gender: boy
School:
School #2
In searching for an 'A* Pozner', Arja's name was the only one that came up that fit the birthdate range for the school he attended. In addition, there are similarities in the pronunciations that would lead me to believe that Arie is Arja's nickname.
I connected Arja to the rest of his family via matching addresses. Arja had a mother, Mindla (b. 1891), and a brother, Mordechaj (b. 1929) that lived with him. They were all deported on the same date, March 15, 1942, during the month of daily deportations to Chelmno.