<![CDATA[This study aimed to analyze the effect of locus of control on junior high school students' interest in learning Biology, particularly the topic of photosynthesis. The study employed a quantitative approach using a survey method with an ex post facto design. The population consisted of eighth-grade students who had studied photosynthesis, with a sample of 65 students selected through simple random sampling. Data were collected using a locus of control questionnaire adapted from Rotter’s scale and a learning interest questionnaire developed from indicators of enjoyment, interest, attention, involvement, and intention to act. The research instruments met the requirements of validity and reliability. Data were analyzed using descriptive statistics and simple linear regression with the assistance of statistical software. The results revealed that locus of control had a significant effect on students' interest in learning Biology on the topic of photosynthesis, with a significance value of 0.000 (p < 0.05). The coefficient of determination (R²) value of 0.319 indicated that locus of control contributed 31.9% to the variance in students' learning interest. These findings suggest that students with a stronger internal locus of control tend to exhibit higher interest in learning compared to those with a predominantly external locus of control. Furthermore, students with an internal locus of control demonstrated better conceptual understanding of photosynthesis. The implication of this study is that strengthening students' internal locus of control should become an important consideration in Biology instruction to enhance learning interest and improve conceptual understanding.]]>
