Bullying in high school

In high school these girls that I have some classes with classmates pick me. They tell me to do their school work and I refuse. So they push me around and I fall. Sometimes they take my backpack and take my homework to submit. One time I told them I would do their homework and on purpose I messed up their homework and they failed and get mad and hit me. Another time they took water and splashed on my jeans and told other students I wet myself. One time I was going to ask a girl I liked to the school dance but one of them showed up and told her I was going to the dance with her(bully) and she kissed me in front of my crush. My crush left and looked sad. Of course I didn't go to dance with my bully so I stayed home that night. These girls won't stop.