Should I skip summer school tomorrow?

Tomorrow is my 16th b-day but I have school as well. :/ I don't want to get up early on my birthday but I need to get my grade up and we cover a lot in a day. I haven't missed any classes so far. I get out at 11 though so I still have the rest of the day ahead of me and I'm having a party at night. Also, theres a girl in my class who has the same b-day as me and she's bringing food for everyone. Do I need to as well? I don't have a lot of money and I'm not friends with anyone in that class.