COMPASS III: teaching L2 grammar graphically on a tablet computer

We demonstrate a prototype of the tablet-based L2 grammar teaching system COMPASS III. COMPASS stands for COMbinatorial and Paraphrastic Assembly of Sentence Structure; for a description of the underlying computational-linguistic software, see [1]. COMPASS invites the student to construct sentences by composing syntactic trees out of lexically anchored “treelets” via the graphical drag&drop user interface provided by tablet and touchscreen. After each move (i.e. each attempt to combine two treelets, or to reorder a branch), the system’s natural-language generator computes all possible grammatically well-formed sentences entailed by the attempted tree. COMPASS provides positive feedback if the student-composed tree belongs to the wellformed set, and negative feedback otherwise. In the latter case, COMPASS may propose alternatives based on a comparison between the student-composed tree and its own well-formed trees (informative feedback on demand). As system feedback may explicitly refer to grammar rules, the learner needs to have elementary syntactic knowledge. COMPASS III targets L2 learners of German with high-school level understanding of word classes and grammatical functions. The user interface allows the student to select words and to move (parts of) trees around through finger or stylus gestures. No typing is required. COMPASS III focuses on word order and case morphology—difficult topics in L2 German.