Teacher’s Performance: Its Relationship to Student Achievement in Mathematics I of National High Schools of Basilan

— This study on “Teacher's Performance its relationship to student's achievement in secondary Mathematics I” was conducted to see the performance of teachers in handling secondary Mathematics I. It aimed to assess teacher's performance following the New Performance Appraisal for Secondary Teachers (NPAST) in terms of the seven task functions. Personal factors were considered to differentiate teacher's performance between urban and Rural School. The study used the descriptive research using a checklist rated by the school administrators to identify teacher's performance. A 50-item was developed to measure student achievement in Mathematics I from a sample of 408 students randomly selected from twenty-two (22) National high schools. Frequencies, Percentages, Chi-square (X2 ) test F-test and T-test were statistically employed to test their significance. Results revealed that: Teacher's performance in teaching Mathematics I gave no significant difference in term of the personal factors like Age, Civil Status, Income, Eligibility, Sex, Teaching, Experience, and Educational Qualifications. Chi-square computation revealed that urban secondary teachers have better performance than the rural secondary teachers in the development of Nation Consciousness, desirable values and habits, Instructional Materials, student's evaluation, Professional growth, and Record-report management. Both urban and rural secondary Mathematics teacher's performance did not significantly differ in terms of the Community/Allied services and being punctual in attendance. A Twofactor analysis of variance revealed a significant relationship that existed between teachers' performance and students' achievement in Mathematics I.The research work recommended that in pre-service education, teachers-to-be must be given the trainings in the seven educations; teachers-to-be must be given the trainings in the seven tasks/functions as identified in NPAST. It is best for neophyte teachers to apply and implement the new teaching methodologies learned in pre-service education. Actual teacher's performance should be a sound basis for decision concerning teacher's promotion, salary increase and further training and scholarship.