The purpose of this study was to verify the effects of team building through physical challenges in third and fourth grade of elementary school physical education. The participants were 5 classes of 126 schoolchildren in 2 elementary schools. The data for analysis were gathered by team building questionnaire focusing on school children’s interactive and cooperative behaviors in physical education class developed by Komatsuzaki and the others in 2001. The descriptions of children’s impressions in every class were analyzed by text mining with KH Coder. The “exercises for releasing body and mind” lessons of the unit consists of 5 times 45 minutes lessons with physical challenges. It was given from October to November in 2013 and in June of 2014. They got exercise of “the edge of a precipice (the rock)” and “giant ball carrying without using hands” in a group consisting of 6, 7, or 8 children in 4th and 5th class.<br>

The results were summarized as follows :<br>

1)The total averages of team building in 5 classes were improved little by little.<br>

2)There were significant differences under 5 % level (1st class < 5th class) in 3 classes.<br>

3)There were increase tendency (1st class < 5th class) in 2 classes.<br>

4) The number of words that were “voice”, “mind”, “cooperation”, “happy” and “can do” in descriptions of children’s impressions in 5th class increased to that in 3rd class.<br>

5)Physical challenges produced good effects on team building.<br>