Excerpt of AR 600-8-2
AR 600-8-2 paragraph 3-1f Actions Prohibited by a Flag states: f. Attendance at military or civilian schools. The waiver approval authority for attendance at military or civilian schools is the DCS, G–3/5/7 (DAMO–TR).
Good News/Bad News
The technical answer is “Yes” it should prevent you from going to school. More than likely if your are still flagged when your school date comes then you will not be able to attend schooling. If your flag is lifted before your school date and your Battalion Schools NCO has not canceled your slot because of the flag then you should be able to attend.