Your dream contains various elements that reflect your emotions, social dynamics, and desires, particularly surrounding your crush and the concept of enjoyment versus responsibility. Let's break it down:

1. Setting and Environment: The dream starts in a school setting, which typically represents learning, growth, and social interactions. The shift to a party atmosphere may symbolize a desire for fun and social connection, particularly in relation to your school life and your crush.
2. Your Crush: The presence of your crush is significant. You feeling happy to be near her suggests a longing for closeness and connection. Her laughter and your interaction may indicate a desire for her attention and affection, but your comment about feeling bad for her shows a mix of empathy and helplessness. This may reflect your real-life feelings of wanting to help but feeling unsure or hesitant to take action.
3. Jumping and Joy: The act of jumping up and down the staircase illustrates a sense of excitement and freedom. It may symbolize your youthful energy and eagerness to engage with your surroundings, especially in the presence of someone you like.
4. The Party: The party represents a carefree, joyous time. It could symbolize your desire for social acceptance and a break from routine. However, the interruption by an annoying classmate suggests feelings of frustration or distraction in your social life. Your choice to hide from this annoyance indicates a desire to escape negativity and fully enjoy positive experiences.
5. The Stranger and the Board Game: The encounter with the stranger who asks you to play a board game signifies a potential diversion from your desires. It could represent unexpected responsibilities or social obligations that take you away from your main goal of enjoying the party and connecting with your peers.
6. The Shift from Party to Blank School: The sudden transition from a vibrant party to a dull, empty school environment symbolizes a loss of joy, energy, or excitement in your waking life. This dramatic change reflects anxiety about fleeting moments of happiness and the unpredictability of social interactions. It can also express fears of isolation or missing out on important experiences.
7. The 6th Standard Children: Encountering younger children practicing for a music competition may represent innocence and the pressures of expectations in both social and academic contexts. Their ignorance about the party's disappearance could reflect feelings of confusion and helplessness in your own social life.
8. Overall Themes: The dream encapsulates themes of longing for connection, the tension between joy and responsibility, and the fear of losing opportunities for fun and social engagement. It may reflect your inner struggles with navigating relationships, especially with your crush, as well as a desire for carefree experiences amidst the pressures of school life.

Advice: Consider reflecting on your current social dynamics and interactions. Are there opportunities for you to express your feelings towards your crush or to engage more fully in social events? It might also be beneficial to embrace moments of joy without letting distractions pull you away. Don't hesitate to seek out enjoyable experiences and connections, as they can lead to personal growth and fulfillment.