Teachers who are already certified, however, should be excused from such testing since teachers, like doctors and lawyers, should be evaluated on the basis of their results. They would justifiably be insulted and alienated by being required to write tests. In Ontario, the government has compounded the provocation by trying to micromanage the number of minutes teachers are obliged to teach and by threatening to compel them to take on extra-curricular activities. Because teachers would be empowered by local decision-making and galvanized by competition with other schools, these policies would actually motivate teachers to improve their personal effectiveness and provide their students with the best possible education. While teacher testing may force some teachers to upgrade their subject mastery, it will not necessarily make them better teachers.
Subject mastery is only one component of effective teaching.
To be successful, teachers must also be able to transmit the relevant skills and knowledge to their students. It is now possible to use each student's previous performance to predict how well he or she should do on tests. If a particular teacher's students consistently do better or worse than expected, it is possible to deduce how effective that teacher is. Ascertaining the value that teachers add to their students' learning, instead of evaluating their subject knowledge or their teaching methods, is a cost-effective way to evaluate not only teachers' subject mastery but also their ability to ensure that the students learn the material. There are jurisdictions that are already doing this.