http://flashcarddb.com/leitner This site explains in one web page the "Leitner 5 deck" Flash Card system, a system as of Fall 2010 rarely implemented on computer server systems of college or high-school language textbook publishers. This system is implemented in a relatively primitive and narrow way in the open source "Pauker" Flash Card system available at www.SourceForge.net. This PI has a not yet public design and coding project to improve upon the "Pauker" code in various ways.