The authors mainly aimed to investigate the following question: Are there any significant effects of the first combined method of a conceptual change approach with refutation text, worksheets, and activities with respect to the second combined method of a conceptual change approach with conceptual texts, presentations, and activities on students' misconceptions and achievement on a 3-tier posttest score measuring Grade 7 basic astronomy concepts when independent variables are controlled? There was a statistically significant effect of the first combined method with respect to the second method at the medium effect size on both misconception scores and achievement scores. This finding clearly demonstrates that use of the first combined method, which included refutation texts with worksheets, eliminated the students' misconceptions and increased their achievement. The second combined method also increased the students' achievement, but almost 40% of their misconceptions remained.