Extracting basis words from Uzbek texts is an important task in the process of classifying the level of Uzbek language knowledge for new Uzbek learners, facilitating the acquisition of academic knowledge by schoolchildren. There are several advantages to extracting basis words for language learners, schoolchildren and philologists. In this study, basis words representing almost all words were selected from among the words in Uzbek language texts. A highfrequency method was used to identify these basis words. Thus, several words can be built using a single basis word. For the investigation, we have collected 35 primary school textbooks for grades 1-4 approved by the Ministry of Preschool and School Education of the Republic of Uzbekistan and named the “Uzbek Primary School Corpus” (UPSC) by the authors. As a result of this process, it was determined that a first-grade student should know 366 basis words, a secondgrade student 462, a third-grade student 486, and a fourth-grade student 512 basis words.