A teacher's goal as a technician is to maximize student achievement as efficiently as possible. Educational technology is looked to to enhance technical efficiency. School instructional policies embodied in a curriculum are thought to provide a program to direct daily teaching. Every experienced teacher knows activities that bring students to learn and that some are more efficient than others. This is what methods courses try to get at.
Many teachers are superb technicians and get results with many different kinds of children.
The problem is that it is difficult to say explicitly just what it is they do. Unfortunately, pedagogical knowledge is still greatly a part of the informal culture of teaching. Many of the causal factors in pedagogy await discovery. Chance often plays a great part. It is difficult to generalize from one successful classroom the circumstances that led to the particular success observed.