A juror attends the whole trial, observing and listening to each witness. After the judge gives them instruction in the law, the twelve jurors meet in private. They discuss the evidence and arrive at a verdict. Jurors must reach a unanimous decision, meaning that the 12 jurors must agree with the verdict. There is no need for this in a trial by judge alone, since the judge knows the law.
Judges give reasons for their decisions.
Lawyers use these reasons to help predict outcomes in future cases with similar facts. Jurors don't give reasons with their verdict. I think it would be educational to sit on a jury. No, you are still too young to sit on a jury. The provinces have the right to decide who sits on a jury.