HQ 4.4:11 "Okrand's Notes":  The most general word for school (a place for learning) is DuSaQ. A specialized school, perhaps translatable as "academy", is 'ampaS. An organization dedicated to scholastic pursuits or research is a yejHaD "institute" or "institution" or a yej'an "society". The distinction between yejHaD and yej'an is not clear, though the former is usually - but not always -used for larger organizations.

FYI the Klingon Language Institute (KLI) is tlhIngan Hol yejHaD.

AFAIK Okrand has never used DuSaQ in a sentence, but the industrious Glen Proechel created several phrases in his ILS materials:

 tlhIngan Hol DuSaQ     KLINGON LANGUAGE SCHOOL

 Hovmey joj Hol DuSaQ   INTERSTELLAR LANGUAGE SCHOOL (ILS)

 DuSaQ lupwI'           SCHOOL BUS

 rIn DuSaQ              "SCHOOL'S OUT"

Many of us use *DuSaQ'a' for "university".