Adolescents generally are less informed, less experienced and less confident about sexual matters and get into lot of sexual related problems such as premarital unprotected sexual indulgence resulting in STDs, illegitimate teenage pregnancies, sexual abuse, violence, exploitation, etc. Therefore it is very important to conduct sex education for adolescence so that they learn about: normal functioning of reproductive system, the healthy relationship with       opposite sex, safe and protected sex, contraceptives, measures to prevent sexual exploitation by anyone in the family, school/college, neighborhood etc. Data was collected using structured questionnaire. Research Approach was used as quantitative approach. Research Design is planned, structure and strategy of investigation of answering there search question in overall planned. And non- experimental approach is use to assess the knowledge. Conceptual framework used for present study is “Modified general system mode” total sample size is 30 and selected by Non probability convenient sampling technique. In these study accessible population 10-12 year school students who meet the designated criteria and who are also available for research study. In this study, inclusion criteria were 10-12 year school student who are willing to participate, 10-12 year school students who are available during the data collection, and 10-12 year students who are able to read and write English. 10-12 year school students who are studying in selected in schools and exclusion criteria was above and below 10-12 year school students who are not willing to participate. The tool for the study was prepared by referring books, internet and related research. The tool was validated by 7 experts of various fields. Suggestion proposed was incorporated and necessary changes are made. The tool was divided 3 sections. section A: it consist of demographic variables, section B consist of background variables and section C consist of 30 question items and each correct response carry 1 mark. The pilot study was conducted by administrating the questionnaire to 5 respondents. The reliability of the questionnaire was done by karl pearson’s formula and tool was found reliable and feasible. The data collection process of main study was done on 18/10//2023 in selected school. Prior visit was made to the selected school to take permission from concerned authorities. After explaining objectives and the purpose of the study, consent was taken from participant. Then test was conduct of duration of 45 minutes. Based on objectives data was analyzed by using various statistical tests, mean, mean percentage, standard deviation, etc. Results in present study shows that the pretest level of knowledge mean score is 13.66 and post- test level of knowledge mean score is 27.13, the pretest knowledge belong to very poor group was 0%, poor 13.33%, would 17%, very good 16.6%, excellent was 0% the posttest knowledge belong to very poor group was 0%, poor 0%, would 0%, very good 10%, excellent was 90%. The mean difference is 13.47. Only belonging area is associated with the result but age, previous knowledge, source of knowledge and gender or not associated with the result. Conclusion, In the study pretest mean score is 13.66 and post-test mean score is 27.13 H1 is accepted that means the study was effective.