Your school can punish you. They have the ability to do so. The extent of punishment is always up for debate. They can definitely suspend you from extracurriculars.
Seth Weinstein, Esq.
Practicing throughout Southern California
This reply should NOT be considered a legal opinion of your case / inquiry. At this time I do not have sufficient factual/legal documentation to give a complete answer to your question and there may be more to the issues you raised then I have set out in my brief reply.
Off campus a marijuana pipe is not illegal, period, end of story. If you were arrested for the marijuana pipe, you need to hire an attorney. There is case law the states the weed pipes are not illegal. You could also challenge the schools decision not to allow you to participate in these activities. Whether you are successful in being able to participate is another story.
You or your parents should contact an attorney to help preserve your rights.
The above information does not establish an attorney client relationship nor is it meant to provide legal advice.