I absolutely want to know that I am an effective teacher and if not, I want to know what I can do to become more effective! Children's voices matter. That's why I am a teacher. How can I move onto the next concept if I'm not making sure they have grasped the one we are currently working on? It's like forcing a 3 month old to walk before they master how to crawl first.
At the end of every year all students should have the opportunity to evaluate their teachers. The evaluations should be anonymous so that the teachers do not hold it against their students if they have them again the following year. Evaluations are important for feedback. A teacher needs to learn what areas they need to improve in. Who better to do those evaluations than someone who has experienced the teacher in action on a regular basis?
High school students should evaluate their teachers because they are the ones that are with the teacher every day. The evaluations should be written so they can be reviewed for reasoning and thoughtfulness, but gathering information from the students can help the administration to make improvement suggestions for teachers and reward those doing a truly excellent job.