I went to break into my school by flying using helium balloons and when I arrived a teacher fought me with a hairdryer and won.
This dream might represent a feeling of wanting to access some part of your past or memories that are associated with your school life. However, the struggle you faced with the teacher in the dream suggests that there could be some resistance or obstacle preventing you from accessing those memories.
The use of helium balloons and flying might indicate a desire for freedom and the ability to rise above your problems, but the fact that the teacher fought you with a hairdryer suggests that there may be opposing forces or authority figures preventing you from attaining that freedom.
Alternatively, this dream might suggest that you are afraid of failure or being caught doing something wrong and hence the struggle with the teacher in your dream represents your fears. It is important to understand what these fears are and how to overcome them.