Team teaching involves a group of instructors working purposefully, regularly, and cooperatively to help a group of students of any age learn. All arrangements that include two or more faculty in some level of collaboration in the planning and delivery of a course. Over the years, a number of researchers have expressed concerns about their co-teaching partners and the types of relationships that they form. These relationships can range from successful to nightmarish, with more students leaning in the Tamil grammatical aspect-Aagu Peyar toward nightmarish. Taking into account these contextual clements, there is a need for a descriptive qualitative study that uses teacher testimonies as the primary avenue for investigating co teaching. To find out the significance of difference between the pre-test and post-test mean scores of the achievement in Tamil grammar Aagu Peyar of the experimental group. To find out the significance of difference between the post-test mean scores of the achievement in Tamil grammar Aagu Peyar of the experimental group with respect to gender, study habit, parents’ educational qualification and occupation. The Team-teaching strategies techniques used to for experimental group. Pre-test: Treatment: Post-test, was conducted by the experimental group. The effectiveness of Team-teaching strategies technique on achievement in Tamil grammar Aagu Peyar was very high. There is no significant difference between the post-test mean scores of the achievement in Tamil grammar Aagu Peyar of the experiments group with respect to gender, study habit, parents’ educational qualification and occupation. The present study has investigated the hard parts in Tamil grammar Aagu Peyar and the construction of Team-teaching strategies techniques at secondary level and it found that the effectiveness and utilization were very high in the case of achievement in Tamil grammar Aagu Peyar. Since, Team-teaching strategies is having effectiveness on achievement in Tamil grammar Aagu Peyar.