The quiet kid in my fourth period isn't just staring at the clock. He's drawing these tiny, perfect skulls in the margin of his history book. I always figured he was just bored, not secretly plotting a metal album cover.
Focus on how that impatience shows their true character, like what the quiet kid is actually thinking. It turns a simple moment into showing someone's hidden flaws or desperation. That always adds way more depth than just describing the clock.