In Greek times it is clear that true education was limited those with much free time and/or the means to pay for private tutors. Due to this, the vast majority of those who were educated were among the small upper class. Elitist "education" was largely based on the ability to speak and persuade; a tool only truly necessary to those who were socially powerful. The later Roman education system was, although theoretically more accessible due to more schools, very similar to that of the Greeks. Those who were "truly educated" were well versed in Latin and were able to speak efficiently.
However, when the Roman power system shifted from political to military, the valued vocation changed in correlation with the valued focus of education. The role of the orator diminished as the role of the soldier increased. In the Greco-Roman times education as an institution was geared to those with time and money, therefore few were able to partake. Clearly if only a small percentage of the populace, in any culture or time-period, has access to information, the impact of that information on society and future generations, as a whole, will be limited.
The medieval education systems' institutions have impacted Education comparably to those of the Greco-Roman period; which isn't saying much. This is due, once again, to the grossly exagerated social caste system that existed during this period. The immense majority of the population had no time for education their lives were consumed by a constant struggle to survive. With all wealth concentrated on the minute land owning populace as well as the Church, education for most was the passing down of a trade from generation to generation as well as basic communication skills.
The only "institutions" were those that were established by, or in order to promote, the good of the Church. Parish, monastic, chantry, and cathedral schools were the extent of medieval education. With all four of these types of schools contributing to one common it is easy to see that the influence of education was limited. Although the ideas taught during the medieval period were, for the most part, rehashed tradition fueled by religious propagandists, highlights such as studium generale and universitas planted seeds for future growth.
Once again, however, due to the exclusiveness of educational opportunities concentrated on those with status, power and, money, the impact on Education that the middle ages had was limited. In contrast to its' insular curriculum of the Greco-Roman period and its' monopolization by the church during the medieval period, education during the renaissance became "enlightened. " As religion was called into question, and the middle class began developing, the educational stagnation of the middle ages also evolved.