The purpose of this study was to determine the relationship between two teaching methods used to teach reading and writing and reading comprehension skills and successes of fifth-grade students. The main difference between the two methods in our research; teaching of the first literacy in the sentence method, determined and sentences with various features, in the voice based sentence method, the sound of the letters in the alphabet is determined by the instruction of the determined group order. The mixed method research design is the process in which both quantitative and qualitative methods are used in collecting, analyzing and mixing the data in a study. The application of the study lasted for two years. The achievement test developed by the researcher was first applied to 1000 fifth-grade students who learned reading and writing by the sentence method, and, then, to 1000 fifth-grade students who learned reading and writing by the sound-based sentence method in the following year. The results showed that there was a significant difference between reading comprehension levels of the fifth-grade students who learned reading and writing by the sentence method versus by the sound-based sentence method. The difference was in favour of the students who learned reading and writing by the sentence method.