Because the law in most places requires students to go to school, schools can discipline you for missing class.
But schools cannot discipline you more harshly because of the message or the political nature of your action.
The punishment you could face will vary by your state, school district, and school. If you're planning to miss a class or two, look up for the unexcused absences for your school and school district. If you're considering missing multiple days, read about truancy. Also take a look at the policy for suspensions. If you are facing a suspension of 10 days or more, you have a right to a formal process and can be represented by a lawyer. Some states and school districts require a formal process for fewer days. You should be given the same right to make up work just as any other student who missed class.