20. Moher, T., Johnson, A. E., Ohlsson, S., & Gillingham, M. (1999). Bridging Strategies
for VR-Based Learning. In Proceedings of ACM SIGCHI 1999 (CHI '99: Conference on
Human Factors in Computing Systems), Pittsburgh, PA, pp. 536-543.
21. Otero, N., Rogers, Y., & du Boulay, B. (2001). Is Interactivity a Good Thing? Assessing
its benefits for learning. In Proceedings of 9th International Conference on HCI, New
Orleans, pp. 790-794.
22. Steuer, J. (1992). Defining Virtual Reality: Dimensions Determining Telepresence.
Journal of Communication, 42(4), 73-93.
23. Nardi, B. A. (Ed.). (1996). Context and Consciousness: Activity Theory and Human-
Computer Interaction. Cambridge, Massachusetts: MIT Press.
24. Roussou, M. (2003). Examining Young Learners' Activity within Interactive Virtual
Environments: Exploratory Studies (Technical Report No. RN/04/08). London, UK:
University College London, Department of Computer Science.
25. Mack, N. K. (1990). Learning fractions with understanding: Building on informal
knowledge. Journal for Research in Mathematics Education, 21, 16-32.
26. Cramer, K., Behr, M. J., Post, T. R., & Lesh, R. (1997). Rational Number Project:
Fraction Lessons for the Middle Grades. Dubuque, Iowa: Kendall/Hunt Publishing Co.
27. Harel, I. (1991). Children Designers. Interdisciplinary Constructions for Learning and
Knowing Mathematics in a Computer-Rich School. Norwood, New Jersey: Ablex
Publishing Corporation.
28. Kafai, Y. B. (1995). Minds in play: Computer game design as a context for children's
learning. Hillsdale, NJ: Lawrence Erlbaum Associates.
29. Lesh, R., Landau, M., & Hamilton, E. (1983). Conceptual models in applied
mathematical problem solving research. In R. Lesh & M. Landau (Eds.), Acquisition of
Mathematics Concepts & Processes (pp. 263-343). NY: Academic Press.
30. Kuuti, K. (1996). Activity Theory as a potential framework for human-computer
interaction research. In B. A. Nardi (Ed.), Context and Consciousness: Activity Theory
and Human-Computer Interaction (pp. 17-44). Cambridge, Massachusetts: MIT Press.
31. Kolb, D. A. (1984). Experiential Learning: Experience as the Source of Learning and
Development. Englewood Cliffs, N.J.: Prentice-Hall, Inc.
32. Vygotsky, L. S. (1978). Mind in Society: The Development of Higher Psychological
Processes. Cambridge, MA: Harvard University Press.
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