The posts above really cover most of what you need to know about students with this disorder except that each one is different in their presentation of the disorder. I have had several students with bi-polar disorder with each being very different in a classroom. The most important thing to me is that you are given the information about the student's condition, and that you inform yourself with at least the information in the two excellent links above from Mayo Clinic. Information is the key as more of our students deal with mental health issues whether students are not diagnosed or misdiagnosed. Trying to meet the students where they are is a big part of a teacher's job. Build a relationship with the student, and many times they can tell you where they are for the day or the hour. Sadly, I think that mental health issues are one of the huge issues in schools today, and too often there is so little help available for both students and teachers.
As pointed out above, "treatment" is not given in school. While some medications are given out at school, students must have a doctor's note about the school administering medication. Outside of that, students with Bi-Polar Disorder tend to have fluctuating moods. At some points, during manic cycles, the student will be elated and full of energy. Other times, during depressive cycles, the student will be depressed and show lack of interest and energy. Another factor is the cycling. Some students may cycle fast ( rapid change from manic to depressive). Others may cycle more slowly.
Unfortunately, medications are hard for a student with Bi-Polar Disorder. In times of mania, one medication is used. In times of depression, another medication is used. Sometimes what happens is a student may be on manic medication and cycle to depressive. The medication then can compound the depressive cycle. The same goes for the reverse. Given that some medications can take weeks to balance out, a student could be on medication for one side of the disorder and the other has already started.
Unfortunately, a child with this condition is usually ostracized by students and misunderstood by teachers. I have only had one student actually diagnosed with this condition in my career. I kept in constant contact with his counselor. I also met him at the door each day, and I could tell his mood by the expression on his face. Then I had a serious of strategies for ensuring that he did not blow up, or that he participated. I was not always successful, but I think he appreciated the effort. It's a hard condition to live with, especially as a kid.
This is a confusing question because a school is not responsible for treatment of any mental disorder and should not be attempting to treat a student. A school can certainly help accommodate a student with bipolar disorder. In K-12 settings, an IEP can be created through the efforts of a school team, parents, and sometimes an advocate for the student. Bipolar disorder involves great fluctuation in mood, from mania, which can present as irritability, sensitivity, or grandiosity, to deep depression. In some instances, people "cycle" rapidly, and in others, a mood can last for months. At the very least, teachers need to keep an eye out for mood changes and provide a "safe" place for a student who is either too high or too low. Students on medication might need reminders to take their meds during the school day, too. Teachers for a student who is bipolar would benefit from some education on the disorder. A compassionate, informed attitude is a must.