TY - CONF A1 - Sui, Li A1 - Dietrich, Jens A1 - Heinrich, Eva A1 - Meyer, Manfred T1 - A Web-Based Environment to Teach Introductory Programming based on a Bi-Directional Layered Notional Machine T2 - Konferenz: 21st Annual Conference on Innovation and Technology in Computer Science Education, 11.-13. Juli 2016 in Arequipa (Peru) Y1 - 2016 UR - https://whge.opus.hbz-nrw.de/frontdoor/index/index/docId/3219 ER -