This study investigated the impact of Parallel teaching on the academic performance of students in the sixth grade in math and their attitude toward school. The research method was experimental, and pretest-posttest with control and experimental groups were used. The statistical population consisted sixth female students in Tabriz in the academic year 94-95, and the sample size is 70 persons that 35 of them in the control group and 35 persons in the experimental group were exposed. In the experimental group, parallel teaching was implemented for 2 months, and in the control group, one teacher taught. The Analysis of ANCOVA was performed on the math achievement of students in the experimental and control group, showed that the students' mathematics achievement between the experimental and control groups had a significant difference. Also, the results of the MANCOVA analysis showed that the attitude towards school in the experimental group (parallel teaching) and control group (one teacher) had a significant difference. This difference in attitude included school environment, students’ perception of education, school objectives valuation, Self-regulation, and attitudes toward teachers and classes. This difference was to using parallel teaching among the students.