My own abilities, including problem-solving ability, calculation ability, expression ability, blackboard writing ability, voice quality and volume, and overall planning ability of curriculum arrangement, etc.
Teaching conditions and requirements of the school, including teaching equipment (such as multimedia equipment, blackboards and other basic equipment), teaching venues, etc. For the requirements, schools at different levels are different. For example, the requirements of key middle schools and ordinary middle schools are much worse, and the requirements of key classes and ordinary classes are different.
To sum up, it is difficult to know whether a junior high school math teacher is good or not without the ability of the problem solver and the school you are going to. But in general, junior high school mathematics is relatively simple, and the focus is on business ability. If the subject is not going to a key middle school or teaching a key class, it should be better.