I think that if the info is important, then you should include it. My CV is organized into the following catergories, and then the items in each catergory are in chronological order (obviously):
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1. Education, Activities, and Honors (dental school listed here, as well as undergraduate school, along with degrees earned).
2. Special experience (List experiences outside of things done associated with school that are pertinent to your qualification for a residency or other position)
3. Professional experience (List any professional experience (teaching, dental office employment, etc that shows additional qualification for or exposure to the field)
4. Research (List any research experience that youve had here. If youve been published, list publication here or in separate PUBLICATIONS section)
5. Professional presentations (List any formal presentations that youve made to professional groups; i.e. table clinic presentations, lectures, etc., along with any resulting awards)
6. Continuing education (List continuing education courses attended, most recent first)
7. Professional societies
8. Personal interests, hobbies, etc.
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So for me, the high school activity, if important to the CV, could go in any number of catergories. The ASDA National Leader would most likely go under #7, if I were listing it.
I hope that helped somewhat. I know that those organizational catergories helped me in compiling mine. And, I literally list each of those catergories on my CV (minus the numbers of course).