Sign is a synonym of Symptom. Pain is a type of Symptom. Suffering is a type of Pain. 
Student can be used for Teaching. Student is the opposite of Instructor. Instructor is related to Teacher. German is a type of Teacher. 
Sign <--Synonym--> Symptom <--IsA-- Pain <--IsA-- Suffering 
Teaching <--UsedFor-- Student <--Antonym--> Instructor <--RelatedTo--> Teacher <--IsA-- German 