<p>If I participate in new extra curricular activities now, when I apply next fall will schools count these, or will they ignore the new ECs because they think my participation is too shallow?</p>
<p>EDIT: Not that I want to take up new activities to impress the schools, I genuinely want to participate.</p>
<p>You should participate in activities that you care about.
When you list your activities on an application, you will list the dates of participation (i.e., 3/2010-present).
The relevance in the admissions process will depend on the depth of your participation, awards won, or importance to the school. For example, a school without a swim team will not give a lot of weight in the admissions process to swimming ECs.</p>