The purpose of this study is to compare the level of interplay in derivational and inflection suffixes that middle school 5th grade students used at written expressions and that used at texts of 5th grades Turkish textbooks. Meanwhile, it aims to also create a list of suffixes that students used. Due to Turkish language have an eclectic structure, it contains a wide range of diverse derivational and inflection suffixes. This richness of suffixes increase both the diversity of vocabulary in language and the diversity of rules about which words are inflected in the sentences. Thus, teaching derivational and inflection suffixes in Turkish language has a significant impact on teaching Turkish language. Moreover, it should be harmony between the texts used as one of the most important teaching materials and the structure of language that students could use. The texts should encourage their language developments and support the acquisition of new language skills. Resultly, the texts used in textbooks needs to be examined multidimensionally. In study, at starting period of 6th grades, written materials were collected from 73 female and 48 male students who studied at 5th grades in 2013-2014 years. Firstly, suffixes were diagnosised in these materials, and then suffixes used at 36 texts that students at 5th grades read in Turkish course textbook was compared with those of in these materials. Furthermore, the lists of frequecies regarding students and texts were created and the level of interplay between these lists was determined. The findings showed that there is any differentiation between suffixes that students could use and that included at texts, and male and female students could also use them at different levels. These differences was showed in lists.