Speech and Language Technology in Education (SLaTE 2013)

Grenoble, France
August 30-September 1, 2013

COMPASS III: Teaching L2 Grammar Graphically on a Tablet Computer

Karin Harbusch, Johannes Härtel, Christel-Joy Cameran

Department of Computer Science, University of Koblenz-Landau, Koblenz, Germany

We demonstrate a prototype of the tablet-based L2 grammar teaching system COMPASS III. COMPASS stands for COMbina-torial and Paraphrastic Assembly of Sentence Structure; for a de-scription 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 wellformed sentences entailed by the attempted tree. COMPASS provides positive feedback if the student-composed tree belongs to the well-formed 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.
   The grammar formalism underlying COMPASS is Performance Grammar, which assumes separate rules for the hierarchical structures of a sentence and the linear order of its constituents. This split allows the student to break sentence construction exercises into relatively small parts. For instance, the learner can select a word and inflect it according to the intended grammatical function without having to worry about the linear position of the constituent in the sentence under construction. At any time during this “scaffolded” sentence construction process, the tree built so far remains visible on the screen, ready to be expanded by attach-ing additional words/treelets; any earlier decision can be undone and corrected.


  1. Harbusch, K. and Kempen, G. “Automatic online writing support for L2 learners of German through output monitoring by a natural-language paraphrase generator”, in M. Levy, Blin, F., Bradin Siskin, C. and Takeuchi, O. [Eds], WORLDCALL, New York: Routledge, 2011, pp. 128-143.

Full Paper

Bibliographic reference.  Harbusch, Karin / Härtel, Johannes / Cameran, Christel-Joy (2013): "COMPASS III: teaching L2 grammar graphically on a tablet computer", In SLaTE-2013, 105.