The relationship between cognitive structure outcomes of students and their test achievement was examined in this study. A question form and two types of tests (a multiple-choice test (MCT) and a true-false test (TFT)) were used to gather the research data. According to the results of this study, extend, richness and integratedness of students' statements significantly correlated to their scores in TFT. Also, richness of students' statements was significantly correlated to their MCT scores. Describing and comparing were significantly correlated with MCT scores, while describing, comparing and inferring were significantly correlated with the students' TFT scores. Therefore, it can be said that tests reflect students' cognitive structures. Furthermore, students with higher order thinking skills can be identified by TFT rather than with MCT. Students' misconceptions about the research topic were also examined, and they were generally on the classification and types of chemical bonds.