Our school has an organization that plans about 10 trips a year around the world. Haiti, Ecuador, Burundi, Peru, etc. Students get clinic hours for traveling on these trips and absences are excused. However, we have a pretty ballin dean of clinics and I'm pretty sure very few schools in the country permit students to take 1-2 weeks off mid-semester (per trip; some students go on multiple) and get clinic hours for mission trips.