During the second semester, we gave a series of supplementary lessons to support the first-grade students who got a failing grade in dynamics in the first semester. To encourage the students to study, we gave the lessons with paying attentions to the following points: (i) inviting the students who wish to join the lessons, (ii) making teaching materials of dynamics including the problems for fundamental mathematics, (iii) giving the supplementary lessons in the students' free time before their club activities begin, and (iv) employing teaching assistants who take good care of the students. From correlation analyses of the academic results of the first semester with those of the second semester, it is concluded that our supplementary lessons effectively expand an understanding of dynamics for the low-performing students.