Tetsuo Ogino Hideyuki Takada Yahiko Kambayashi Visualizations and Analyses of Elementary School Students? Actions on Squeak Environments. 42-47 2004 conf/c5/2004 C5 http://csdl.computer.org/comp/proceedings/c5/2004/2166/00/21660042abs.htm db/conf/c5/c5-2004.html#OginoTK04