Teachers Unions and tenure

I think that teacher unions and tenure can be beneficial, but they seems to cause more problems then do good.  I feel like some older teachers take advantage of tenure and become lazy.  Some teachers refuse to change and adjust to the students, which hurts the school.  I love the security of tenure, but it's sad that it gets taken advantage of by some, which gives it a horrible reputation.

I am from a small area where a lot of schools are downsizing.  I would hate to be one of two second grade teachers, in a school that now only needs one teacher and my co-teacher has tenure, and I didn't so no matter how good of a teacher I was, I would ultimately lose my job.  I think this happens a lot, and it is sad.  Teachers should be kept because of their quality, not because of how long they have been at the good.  Teachers should constantly receive reviews, and be improving their teaching strategies.  The best teachers in the school should be the ones that have all the experience, not the ones straight out of college.  The new teachers should be able to come to a new school and look up to the older teachers.  If the old teachers don't keep up with the change, the new teachers have no one to learn from.