International examinations such as TIMSS play a major role in determining the quality of the educational process. TIMSS results show that students have various deficiencies. Studies investigating the causes of this failure draw attention to textbooks. In this study it was aimed to examine the objectives in the 2018 mathematics curriculum and the tasks related to the data handling content domain from 4th to 8th grade textbooks according to TIMSS cognitive domains. In addition, similarities and differences the objectives in the curriculum and the tasks in the textbooks have with TIMSS 2019 cognitive domains were examined. Document analysis method was used and content analysis was conducted. The results revealed that the tasks in all the textbooks are predominantly in the cognitive domain of applying, followed by the cognitive domains of knowing and reasoning. In addition, it was determined that the objectives at all grade levels were predominantly concentrated in the cognitive domain of reasoning. Based on the results obtained, some suggestions were given.