Dreams that take place in school settings often relate to learning, social dynamics, and personal growth. Your dream seems to be rich with themes of relationships, choices, and self-perception. Here are some elements to consider:

1. Classroom and School Environment: These settings usually symbolize a place of learning or self-assessment. You may be reflecting on your past experiences, lessons learned, or unresolved issues from your school days.
2. Friend Dynamics: The situation with your friend who didn't want to go to the movies might indicate feelings of rejection or fear of abandonment. It could suggest you are dealing with social anxieties or concerns about your relationships in waking life.
3. Feeling Watched: Your fear that the girl you stopped talking to could hear what you were saying may reflect feelings of vulnerability or guilt about past interactions. It may suggest a need to address unresolved feelings or conflicts with people from your past.
4. Avoidance and Pairing Up: Your intention to avoid pairing with your best friend (bsf) to intentionally hurt her feelings could indicate underlying tension or conflict in your relationship. It may be worth exploring how you feel about your friendship and any unresolved issues that might be impacting it.
5. Body Scanning and Security: The TSA-like line could symbolize feelings of being scrutinized or judged. You may be feeling pressure to conform or anxious about how others perceive you.
6. Classroom Activities: The various activities in the classroom, including the lemon and salt ritual, might represent the varied experiences and pressures you are facing. This could hint at trying to fit in or conform to certain social norms.
7. Nervousness About Personal Information: Your anxiety over someone finding out personal information indicates a sense of vulnerability. You may be feeling exposed or worried about how others perceive your life.

Overall, your dream seems to express a mixture of anxiety, social dynamics, and the challenges of navigating relationships. It might be beneficial to reflect on your current friendships and any unresolved feelings you have towards them. Consider having open conversations with those involved to address any lingering issues, as this may help to alleviate some of the anxieties reflected in your dream.