What qualifications do I need to teach piano?
It depends on what level you want to teach and where. To teach at a university or conservatory you’ll need to have at least a graduate degree, or be an established performer. To teach in public schools you’ll need to meet the certification standards of the local school district. To teach private students you’ll need to be able to prove to your potential students that you’re capable of teaching and are proficient at playing piano. Degrees, certifications and recommendations would do that. Keep in mind that Grade 8 is an indication that you are a capable performer, but it doesn’t say anything about your ability to teach.