What are the consequences for a student caught with marijuana?

Possession of marijuana is a crime. If the possession was detected near or on school grounds, additional charges are filed in addition to "possession". If the quantity was an amount sufficient to qualify as "intent to sell" (even if the student never sold drugs or intended to sell), the charges again will probably be increased to intent to sell.

The student would likely be arrested and would need to appear in court to make a plea of guilty, not guilty, or nolo contende and then receive a sentence. There are many variables in sentencing.