1. Department of Human Development and Department of Curriculum & Instruction Teachers College; Columbia University; New York NY USA
2. Human-Computer Interaction Institute, Department of Mathematics, Science, and Technology; University of Illinois Urbana-Champaign; Champaign IL USA
3. Center for Teaching & Learning, Department of Applied Linguistics & ESL, Learning Sciences Institute, Thompson Writing Program; Carnegie Mellon University; Pittsburgh PA USA
4. Department of Computer Science, Computational Psychometrics Research College; Columbia University; New York NY USA
5. Georgia State University; Atlanta GA USA
6. Arizona State University; Tempe AZ USA
7. Duke University; Durham NC USA
8. North Carolina State University; Raleigh NC USA
9. Educational Testing Service; Princeton NJ USA