Collect data by sitting in on the teacher's class and observing them during an average class day. Look for timeliness, ability to effectively convey subject matter, class management, how they relate to their students, knowledge of subject and appropriate use of teaching materials. Organize your notes afterward and look over them for an overall direction for your evaluation and what points you want to touch on.
Start with a basic description of the teacher's subject matter, their experience teaching and any relevant background information about them. Fill out any necessary basic information fields if you are completing a structured evaluation form.
Discuss the criteria for effective teaching at your given institution and how the teacher you're evaluating meets or fails to meet them. Adequately and thoroughly address any criteria mentioned in the evaluation form or as defined by state law or tenure requirements.
Include opinions from student evaluations, if they were also conducted. Create an accurate impression of student reception to the teacher based on the general thoughts from the evaluation.
Conclude your evaluation with some final statements about the teacher's efficacy in the classroom, their overall ability to conform to school standards, and your personal impressions of their skills. Include suggestions for improvement or recommendations for tenure if appropriate.