FreeCol:Model.building.college.description/en

A colony with a population of at least 4 may build a schoolhouse, which enables some master craftsman to teach an unskilled colonist their trade. As soon as the population reaches 8, it can be upgraded to a college, in which additional trades can be taught by two colonists. Once the population reaches 10, the college can be replaced by a university, at which all trades can be taught by three colonists.

A college allows teaching skill faculty 2.