[1] Univ Hong Kong, Fac Educ, KM&EL Lab, Hong Kong, Hong Kong, Peoples R China
[2] East China Normal Univ, Dept Educ Informat Technol, Shanghai, Peoples R China
[3] Open Univ Netherlands, Welten Inst, Heerlen, Netherlands
[4] Univ Oulu, Oulu, Finland
[5] Univ North Texas, Dept Learning Technol, Denton, TX 76203 USA