The word 'good' can have quite a few interpretations. For the purpose of this blog post, it is assumed that "good" here means "Effective", that is, a teacher can impart his knowledge and whatever other values it is his responsibility to spread to his charges. It is also assumed that the teacher under discussion is one who teaches secondary school and/or junior college.
First of all, a teacher must know his profession thoroughly. He must know his subject for beyond the point he intends to teach. He needs to be an expert in his field. For example, if he is teaching chemistry, he should know all the chemistry-related fields and careers out there. He should also need to be able to relate how Chemistry is related to our everyday life, and not some abstract concepts and theories. The teacher needs to translate those abstract concepts and turn them into interesting things that the students can relate in their everyday life. It is only in this way, he can then make cross references and answer all the questions that arise in the minds of his students.
First of all, a teacher must know his profession thoroughly. He must know his subject for beyond the point he intends to teach. He needs to be an expert in his field. For example, if he is teaching chemistry, he should know all the chemistry-related fields and careers out there. He should also need to be able to relate how Chemistry is related to our everyday life, and not some abstract concepts and theories. The teacher needs to translate those abstract concepts and turn them into interesting things that the students can relate in their everyday life. It is only in this way, he can then make cross references and answer all the questions that arise in the minds of his students.