First, look at your activities and ask your self, do I really have more than 10 significant activities. Playing JV tennis only in 9th grade. Does that need to be on your resume? No. That 2 hours that you helped at the food shelf sophomore year? Nope.
Colleges are looking for activities that you have been engaged in ideally for multiple years and for significant hours. No, there is no definition of “significant” but I think most of you can figure it out if you are honest with yourself.
Second, can any of your activities go in the academic honors section of the common app? National Honor Society for example is a common activity that can easily go in the honors section. If you have been significantly involved in NHS during high school you may still want it as an activity but for many students, putting it just in the honors section is sufficient.
Third, is it possible to combine several activities into one heading? For example, if you have had 5 volunteer opportunities but none of them have been long term or for many hours, you many be able to combine them into one activity listing for volunteering.
For most students, these three options will take care of any problem you have fitting the activities into the space provided.
But, every year, I have one or two students that truly have more than 10 significant activities. The solution is to include a mini resume of those extra activities in the additional information section. Only list the extra activities that didn’t fit, not all of your activities.
Activities are important for admissions particularly for selective colleges. But there is a reason that the colleges only have 10 activities on the common app. Quality of activities is always more important than the quantity of activities.