Many of the certificates that in-service teachers could take depended on the field of their profession and the skills they wanted to improve. Here are some certificates that might be useful: 1. Education Teacher Qualification Certificate: This is one of the most common certificates for in-service teachers. It proves that you have the professional knowledge and skills to teach the corresponding subjects. 2. Mandarin Level Certificate: As a teacher, you need to have good language skills. The Mandarin Level Certificate can improve your oral and written skills. 3. Counselor certificate: If a teacher needs to deal with relationships with students, parents, or colleagues, a counselor certificate can help them better understand and deal with various emotional and psychological problems. 4. Education Management Certificate: If a teacher wants to have an in-depth understanding of education management, school management, and education policy, the Education Management Certificate can help them expand their knowledge and career development. 5. Education programming certificate: With the development of digital education, education programming certificate can help you better adapt to this educational model and improve your teaching skills. 6. Nutritionist certificate: If teachers need to provide health and nutrition education to students, a nutritionist certificate can help them better understand nutrition knowledge and provide better nutritional support to students. The above are just some of the certificates that might be useful. You still need to choose the right certificate according to your career field and career development goals.