Interpersonal skills include: teamwork, responsibility, leadership, motivation, etc.
To develop these skills one can take on more leadership roles and do more team based work. In school projects a student can lead a group project or a school club, through this leadership the student would be able to learn how to motivate and assist people in his/her team or club. Through this method the student will be able to handle more responsibilities, take on more leadership roles, work on his/her motivational skills so that his/her team or group remains well motivated, and become a better team player as the experience of being in a team and leading it will teach the kid how to deal with team issues and how to negotiate between team members, as well as how to consider their opinions and how to communicate with each of them.