The aim of this study was to investigate the effects of practical work enriching instruction of biology lessons on 9 th grade students‟ attitudes toward biology lessons and thair achievement based on students‟ success. This study is conducted with 59 students of 9 th E in diaspora secondary school thought biology course in 2019 G.C. And the sample selected randomly from the total 8 sections of 9th graders. Attitude pre-test , attitude post-test, achivement pre-test and achivement post- tests are employed for all participants in addition to intervewing four students randomly selected from the total participants. Experimental teaching method was used for two weeks for all participants on one of the lesson selected randomly in the text called osmosis and diffusion. . attitude pre-test, attitude post-test, achievement pre-test and achivement post - tests are employed for all participants in addition to interviewing four students randomly selected from the total participants. The test was applied to students in two different times. The first test was applied before and the second test was applied after the intervention. Paired sample (dependent sample) t-test was used to compare the two results of students‟ attitude and achievement test by using 5 % level of significance. According to the research results, it was found that experimental teaching method was more effective in the attitude and achievement level of students in some biology lessons, attitude and achievement has positive correlation. So the study recommend that high school biology teachers should plan their lessons in more practical way to boost (enhance) learners attitude as well achievement. All stakeholders including curriculum planners should take part in the planning process.