Term limits for teachers

One thing that I would like to see happen in our public schools is giving teachers a limited number of years that he or she can teach.  I think 3, 4, or 5 years as a teacher is enough.  To keep things fresh and bring in new perspectives, I think there should be an on going rotation of teachers.  Many people can teach and many have something to offer.  However, not everyone wants a career for life as a teacher.  Term limits would also force out those who are not at the standard that they should be.