The purpose of the study was to investigate the impact of teaching methods on pupil's performance in mathematics in Meru south district Kenya. The specific objectives of the study were; to determine the various types of teaching methods and their effect on performance of learners in mathematics, to investigate the hindrances to effective teaching of mathematics and to determine gender differences that exist in the performance of mathematics in Meru South district Kenya. The methods used for data collection were questionnaires to the pupils and interviews with the parents. The study revealed that Problem-Oriented Curriculum, corporative group work or collaboration, demonstration, .discussion and questioning were some of the teaching methods used by teachers in teaching mathematics The study revealed that the hindrances to effective teaching of mathematics were use of unqualified and un trained teachers, use of poor teaching methods, lack of learning resources among others. The study revealed that that gender differences in mathematics are caused by girl 's bad attitudes towards the subject, society 's attitudes towards girls and mathematics all these contribute to differences in performance between girls and boys.