学窓 is read as がくそう (gakusou) and means school.
がくそう
gakusou
がくぶ
department of a university
がくえん
educational institution
がっか
department (university, etc.)
がっき
school term
がくわり
student discount
がくひ
tuition
がくせつ
theory
がくい
(academic) degree
がくない
within the school
がくじゅつ
science
がっこうほうじん
(legally) incorporated educational institution
がくしき
scholarship