Toby Dragon Ivon Arroyo Beverly Park Woolf Winslow Burleson Rana El Kaliouby Hoda Eydgahi Viewing Student Affect and Learning through Classroom Observation and Physical Sensors. 29-39 2008 Intelligent Tutoring Systems http://dx.doi.org/10.1007/978-3-540-69132-7_8 conf/its/2008 db/conf/its/its2008.html#DragonAWBKE08