This study aims to clarify how pupils' observations of the demonstrations video were transformed during gymnastic classes. Second graders of the elementary school were asked to describe the process of the movements seen in the same video before and after their gymnastic classes. We then compared the five cases and the results are summarized as following points.
(1) Because they practiced on the basis on the teacher's instruction, their descriptions on the basis of it increased.
(2) After the classes, some pupils described their awareness about time lag between some movements. And the numbers of their descriptions about movement conception of force increased.
(3) It was said that second graders tended to describe the first phase of the technique. After classes, however, they described the major phases of the technique.