Several biases in evaluation process of professors by undergraduate students

The evaluation of the teaching process uses questionnaires applied to the students, giving them the power of be anonymous in their responses. However, if at the end of the course some students get low grades, at the moment of their responses to the questionnaires they can have an attitud of revenge against the teacher, manifested by bad evaluation to the teachers. There are other situations that interfere with students responses leading to biases in evaluation process. We reviewed factors that interfere in the teacher evaluation through questionnaires causing biases and, we also tryed to find alternatives to diminish biases in evaluation. We search original articles and reviews in web sites databases about biases in professor evaluation process and comments about avoid these biases. We also conducted a manual search for relevant articles in the reference lists of articles. Several factors can be biases in teachig evaluation proccess as feeling of revenge, more difficult course, younger students and gender male students evaluators. Non-white teachers, female teachers, older teachers, non-charism teachers, non-good look teachers also get lower grades. Teacher evaluations through questionnaires must be viewed with caution due to several biases.  Since questionnaires are difficult to be replaced in the evaluation of teachers, we discuss alternatives in order to avoid injustice to the teachers.