The purpose of this study is to examine how and in what ways the dimensions of the nature of science are included in the 6th, 7th, and 8th grade science textbooks taught between 1926 and 2018 and to determine how these dimensions are represented in textbooks based on curricula shifts. In this study, a total of 24 textbooks allowed by the Ministry of National Education to be used in schools were examined by using the document analysis method. Textbooks were prepared according to the science curriculum published in 1926, 1948, 1968, 1992, 2000, 2004, 2013, and 2018. Textbooks were evaluated in eight dimensions, including empirical, inferential, tentative, creativity, social and cultural structure of scientific knowledge, theory-driven (subjectivity of scientific knowledge), myth of the scientific method, and the nature of theories and laws. The representation of the dimensions in the textbooks was determined by using the rubric developed by Abd-El Khalick, Waters and Le in "Journal of Research in Science Teaching" 45:835-855, 2008. As a result of the analyses, it was concluded that the representation of the dimensions of the nature of science was inadequate in all examined textbooks. While most of the textbooks include empirical, inferential, and tentative dimensions of the nature of science, creativity, theory-driven, and social and cultural structure of scientific knowledge are given little attention; myth of the scientific method, the nature of theory, and laws are almost never taken into consideration in the textbooks. It has been observed that the representation of the dimensions of the nature of science is at a slightly better level in the textbooks of the 2000 and following curricula. Therefore, it is concluded that all curricula are inadequate in general because the dimensions of the nature of science are represented in a more indirect approach in the science textbooks examined.