In the year -168 SA (-163 SI), Andrew Grades, then Headmaster of Salem Institute, ordered the creation of the Determining Globe, in order that students coming to the school could impartially be sorted into the four houses. While there was some small adjustments over the next few years as to what qualities each house laid claim to, by -159 SA their structure became settled into the pattern which it still holds today.

The Famous Determining Globe is what decides what house students are placed in at Salem. The Globe is contained in a special, hidden room at the center of the school. There it sits on a wooden stand, surrounded by bronze curtains, with no windows and no doors. Once a year a door does appear, however, and it is then that the Head of Salem enters the room to retrieve the names and house placing of new students, before sending out acceptance letters. Unlike the Sorting Hat at Hogwarts, the Determining Globe puts students exactly where they ought to be, without factoring in choice or desire. This promotes the Salem ideal that all houses are equal, and is intended to encourage interhouse relationships.