Talk It Out
If we have a tornado of negative thoughts in our heads, it will be harder to calm down and to stay calm. We might take a few deep breaths or distract ourselves, and that "pumps the brakes" on our stress (e.g., anger, frustration, anxiety) for a while. However, as soon as we start thinking about what made us stressed in the first place, those emotions will start to bubble up again.
Most of the time, it really helps to find someone to talk to. This could be a friend, a family member, a teacher, or another responsible adult. Find someone who will give you their full attention and really listen. You can spot this person because they'll be looking at you, nodding, etc. while you talk. When you pause, they might repeat part of what you said or ask questions to be sure they understand you.