The purpose of this paper is to report the practice of a multigrade CLIL activity with the Jigsaw Method at Kosen. The author designed and revised a CLIL activity in fifth, third, and first graders’ English classes, referring to the viewpoint of instructional design. The first graders read English reports on technology written by the third and fifth graders in the expert activity, and they combined the ideas on the reports into a new technology in the jigsaw activity. The results of the questionnaires suggest that the cooperative CLIL activity was effective in motivating the students.