Sensible and knowlegeable person would do any sort of good things unbiased, and it seems the said principal, in good interest and intention has got this idea. But students on their part couldnot well be said of unbisedness based on dwindling nature of children. They may be influenced, good or bad, very easily.
Hence, whatever outcome, we maynot find it a role model to follow in other schools as well.

it is the right way.

I am all for it. Other schools` principals should also follow this very good example.

If the process of judging the teachers is purely on liking or disliking of students then it is not good. But if grading of teachers is done on some standardized frame work which include grading by the means of, teachers communication skills, ability to clear doubt, ability to judge the children's strength and weakness etc then its really very good practice.

in some of the schools it is there
performance of students is judged
and they were allowed to opine on teachers

this system exists in University of Pune but the students there are all Post Graduates. there is a difference between mature people and kids. that is why voting rights are given to people who are 18 and for the same reason official age for marriage is 18. we cannot give the right to judge to children who think very much emotionally.

what i feel instead its student it should hv been with the parent who can adjudged the teaching method more vigourously ..further more may be 1% student who really can adjudged their teacher but for remaining it may be otherwise ...