I feel that global collaboration is an important thing for students to have. The only global collaboration I have participated in is the Flat Classroom Project, and I learned a lot through it. The project revolved around how technology is changing our world. But the more important thing I got out of it was how to work with others better, and deal with a wider variety of problems that could interfere with the progress of your project, like time zones and differing cultures.
I think that up until high school, it is not necessary to have a global collaboration experience, because once in high school, you begin to need collaboration skills for group projects. It also starts to get you prepared for the real world where tons of jobs require collaboration, and some even on a global scale.
