YOU SAID:
my teacher is a science one
INTO JAPANESE
私の先生は理系です
BACK INTO ENGLISH
my teacher is a science major
INTO JAPANESE
私の先生は理科を専攻しています
BACK INTO ENGLISH
my teacher majors in science
INTO JAPANESE
私の先生は科学を専攻しています
BACK INTO ENGLISH
my teacher majors in science
Come on, you can do better than that.