In: Gautam Biswas; Susan Bull; Judy Kay; Antonija Mitrovic (Hrsg.). Proceedings of the 15th International Conference on Artificial Intelligence in Education - Lecture Notes in Computer Science. International Conference on Artificial Intelligence in Education (AIED), June 28 - July 1, Auckland, New Zealand, Pages 544-546, Vol. 6738 2011, ISBN 978-3-642-21868-2, Springer, Berlin, 2012.