<p>You can talk about whatever you want to. What really matters is how you talk about it. You could literally talk about grass growing and end up with a great essay.</p>
<p>High school ECs are less relevant than college ECs, so I wouldn’t list them as your ECs in that section if it can be avoided, but if you can tie a HS EC to something more important, I don’t think that would be an issue.</p>