Nobuyoshi Koga*, Takaaki Kimizu, Masatora Sakamoto, and Yoshihiro Furukawa
Chemistry Laboratory, Department of Science Education, Graduate School of Education, Hiroshima University,
1-1-1 Kagamiyama, Higashi-Hiroshima 739-8524, Japan, nkoga@hiroshima-u.ac.jp
Received October 9, 2008. Accepted May 22, 2009