Dreams about school often reflect feelings related to learning, growth, and self-evaluation. In your dream, the fact that you missed an entire semester of math class may symbolize feelings of being unprepared or overwhelmed in some area of your life. This could relate to work, personal projects, or relationships where you feel you might be falling behind or not meeting expectations.

Encountering your old math teacher, who reassures you, suggests that you have the support you need or that there are resources available to help you catch up. This could represent a part of yourself that is wise and nurturing, reinforcing the idea that it's okay to seek help when needed.

Your anxiety about not passing indicates a fear of failure or not measuring up, which is common in dreams related to school. It might be worthwhile to reflect on areas in your waking life where you feel pressure to succeed or where you fear you're not doing enough.

To address these feelings, consider setting small, achievable goals in the areas where you feel behind. This way, you can gradually work towards feeling more confident and capable. Remember, it's okay to seek help and support from others, just as you experienced in your dream.