Abstract. The study aimed to address gaps in life science literacy by developing a laboratory worksheet tailored to the least learned competencies of students. A quasi-experimental design with a non-equivalent group approach was used, involving 21 students as the experimental group and 11 as the control group. A standardized test was initially administered to identify the students' least learned competencies, followed by creating a pretest and post-test questionnaire validated by experts. The laboratory worksheet was then developed based on these identified competencies and administered to the experimental group. Results indicated that the worksheet was highly effective, with the experimental group's proficiency level increasing from 30.00 to 69.68, more than double the initial score. Statistical analysis revealed a significant difference between the scores of the control and experimental groups, confirming the laboratory worksheet's efficacy in improving student proficiency in life science. The findings imply that targeted instructional materials, such as the developed worksheet, can significantly enhance learning outcomes, suggesting their broader application in educational settings to address specific competency gaps.

Keywords: Life science; Laboratory worksheet; Quasi-experimental design; Competencies, Proficiency level.