Building high-quality teaching force is the basic guarantee of the comprehensive implementation of quality education. In order to establish a scientific and rational evaluation of the teaching system, to evaluate teachers' teaching objectively and fairly, to mobilize teachers' enthusiasm, initiative and creativity fully, to form a mechanism of analysis, evaluation and feedback, to create a good teaching environment and to encourage teachers to improve and perfect themselves continually, it is necessary to establish an evaluation index system of the teaching and determine weights of the various indicators by documentation and investigation. A mathematical model is established by using the theory of the Unascertained Rational Number. It evaluates teachers' teaching comprehensively from these four aspects: the accomplishment of teachers, the quality of the teaching progress, the reform and research of teaching, teaching effects. The objective and fair evaluation result is obtained by using the model of the Unascertained Rational Number. By comparing with the result of "the average", it illustrates the superiority of the Unascertained Rational Number. The objective and fair result helps them promote the teaching quality and optimize the building of teachers' contingent in primary and secondary schools, also provides a scientific and feasible way for evaluating teachers' achievements.
