This study investigated the effectiveness of conceptual change texts oriented instruction accompanied by demonstrations in small groups on students' ecology achievement and attitude towards biology. 78 ninth grade students in a public high school participated in this study. While the control group was taught with the traditional method, the experimental group was instructed by the conceptual change approach within small groups in five weeks time period. Conceptual change texts were prepared for remediation of students' misconceptions about ecology. Conceptual change texts were supported with worksheets requiring demonstration tools and visual aids. Independent samples t-test was used to analyze the data. The results revealed that the conceptual change approach oriented instruction made a statistically significant difference between the experimental group and the control group in students' ecology achievement in favor of the experimental group, although there was no statistically significant mean difference between the experimental group and the control group in students' attitude towards biology.