1. Teaching methods and effects: We can observe their teaching style and students' feedback. You can ask students whether they like a teacher, whether they find the course interesting and whether they have made progress in their studies.
2. Subject expertise: consider the professional knowledge and experience of two teachers in the subject or field you are interested in. You can try to ask them questions, or observe their teaching methods to understand their professionalism in subject knowledge.
3. Personal interests and needs: If you have special interests or needs for a teacher or course, such as humorous teachers or practical courses, you can make a choice accordingly.
4. External evaluation: refer to other people's evaluations, such as school administrators or other students, but please note that this is only for reference, because everyone's views may be different.
No matter which teacher you choose, you should make sure that you are satisfied with the teacher's teaching method and style, and you can learn and develop under his guidance.