5Perkins. Distributed cognitions: Psychological and educational considerations [ M ]. Cambridge, UK : Cam- bridge University Press, 1999.
6Wenger, E.. Communities of Practice : Learning, Meaning, and Identity[ M ]. Cambridge University Press, 1998.
7J. L. Lemke. Cognition, context and learning: A-social semiotic perspective. In D. Kirshner & J. A. Whit- son. Situated cognition : Social, semiotic, and psychological perspectives [ M ]. Mahwah, NJ : Lawrence Erl- baum Associates, 1997.
