Interfaces are data types that are very useful for providing abstract and organized views on programs and APIs, and opportunities for writing more generic code and for reuse. Extract interface refactoring is a well known local refactor-ing which is commonly used in development tools. Beyond that local refactoring, there is a need for mass extraction of an interface hierarchy from a class hierarchy. In this paper , we made an experience with master students to put into practice an existing Formal Concept Analysis (FCA) based approach for solving that problem. The results show that the data selection (selected datatypes: interfaces, abstract classes, concrete classes; attributes; attribute description ; methods; method description; etc.) was not obvious as it was expected to be, and that the students used the approach more as an analysis technique that would guide the extraction, than as a turn key solution.