Unique list of names, not located in two other lists
I have a google spreadsheet that is being used to develop student schedules. Students are separated into one of two "houses" of teachers on the grade level roster sheet, then each house is scheduled on another sheet in the workbook.
I need to generate a list of students who are marked for "beta" house on the grade level roster (students from all houses), but whose names are not yet listed on the house scheduling sheet.
I have tried
=Unique(Filter(Roster!A:A&A3:A30,Roster!B:B="Beta"))
as well as
=Filter(Roster!A:A,Roster!B:B="Beta",<>A3:A30)
I made some loose attempts with the Query function, but I really have no idea what I am doing with that function yet.
The reason for the inconsistent range sizes is that students with special needs are scheduled first, and then other students (Speech/504/ELL) are scheduled as another layer of the process.
The Grade level roster sheet:
The House scheduling sheet:
=Filter(Roster!A:A,Roster!B:B="Beta",ISNA(MATCH(Roster!A:A,A3:A30,0)))