Krittaya Leelawong Karun Viswanath Joan M. Davis Gautam Biswas Nancy Vye Kadira Belynne John D. Bransford Teachable Agents: Learning by Teaching Environments for Science Domains. 109-116 2003 conf/iaai/2003 IAAI db/conf/iaai/iaai2003.html#LeelawongVDBVBB03