This study was conducted to determine the effects of a lecture about the harmful effects of smoking on the knowledge and attitude of the grade 9 students from the Municipality of Mahayag, Zamboanga del Sur. Focusing on the age groups 13-15, who were found to be the most susceptible of developing the habit as international surveys suggest. In this study, the grade 9 students from Daniel C. Mantos Highschool and Mahayag School of Arts and Technology were given an exam with questions pertaining to both knowledge and attitude about smoking. The exam consists of 10 items for the knowledge portion, and 9 items for the attitude portion. This exam was given a week prior to giving a 30-min lecture on the harmful effects of smoking, and the same exam was given as post test 1 a week after the intervention, and post test 2 two months after. There was a significant increase in the knowledge of the grade 9 students from the pretest (mean score of 3.50) to the post test 1 (6.68), with a significant decrease in knowledge following post test 2 (5.56) signifying knowledge decay. There was also a significant increase in the number of respondents with good attitude towards two of the nine attitude questions. Specifically, the number of respondents who believed that smoking signifies that one is a grown up decreased, and the number of respondents who believes that smoking is a personal freedom and others have no right to interfere also decreased. It is concluded in this study that the use of lecture is effective in improving the knowledge of the grade 9 students from the Municipality of Mahayag, Zamboanga del Sur about smoking, however, it was only effective in improving some of the attitudes of the students towards smoking. The researcher would recommends the inclusion of practices in future studies, as one of the limitations of this study is it only measures the knowledge and attitude of the respondents.

Keyword: Improving knowledge Attitude