Where co-education was first time introduced?

Pinpointing the very first instance of co-education is difficult due to a lack of consistent historical records and varying definitions of what constitutes "co-education." However, some of the earliest known examples include:

* Ancient Greece: Some philosophical schools, like those of Plato and Aristotle, are believed to have included both male and female students, although this was likely limited to a privileged elite and not representative of widespread practice.

* 19th Century United States: Oberlin College, founded in 1833, is often cited as the first co-educational college in the United States to offer equal educational opportunities to women and men, granting degrees to both sexes. It's important to note that other institutions might have admitted women earlier but perhaps with less equality or limited access to specific courses or programs.

Therefore, there's no single definitive answer. While some argue for instances in ancient times, Oberlin College is frequently cited as a significant early example of a *formal* and *equal* co-educational institution.