Built in 1740, built during the reign of Sultan Mahmud (1730-1754) , this is an elementary school for primary education on the grounds of the mosque. The notice did not indicate if there was some connection with the mosque proper, like the children being kids of people working there. The Turkish name is Sibyan maktab.

It is situated between the current entrance and exit. Or:
It is the last building on the grounds to the right one passes before leaving.