Pedagogue: A teacher of children; one whose occupation is to instruct young children; a schoolmaster. 

These days a pedagogue carries a negative connotation.  A pedagogue is a strict teacher, or a pedant.  Dolores Umbridge. 

Pedagogue comes from the Greek παιδαγωγός (paidagogos), which derives from παῖς, παιδός (child) and ἀγωγός (guide).

In ancient Greece, a “pedagogos” was a slave who accompanied children to school. 

Translation: In ancient Greece, boys had to be escorted to school, because some things never change.  Send a boy alone to school, and he will not make it to school.