Objectives The purpose of this study is to analyze the educational vocabulary grades of expository and narratives contained in the entire volume of middle school Korean textbooks of nine publishers of the 2015 curriculum to obtain implications for the development of Korean textbooks and vocabulary education in middle school.
 Methods To do this, the study built a corpus of expository and narrative texts in all Korean language textbooks for grades 1-3 in middle school, extracted 120 high-frequency content words from each text using the Mecab morphological analyzer in Python after preprocessing, and analyzed them according to the educational vocabulary grade presented in previous research. The study also calculated the vocabulary grade by text type and grade, extracting the top 50 high-frequency words from each text.
 Results In the corpus of expository texts, the vocabulary grade was 1st grade (80.9%) > 2nd grade (10.8%) > 3rd grade (6.7%) > 4th grade (0.8%) = 0th grade (0.8%) in descending order. In the corpus of narrative texts, the vocabulary grade was 1st grade (95.8%) > 2nd grade (3.3%) > 0th grade (0.9%) in descending order. There were no 3rd or 4th grade words in the narrative text corpus. When comparing by grade, in the corpus of expository texts, the 1st and 3rd grades had the order of 1st grade (84%) > 2nd grade (8%) = 3rd grade (8%) in descending order, and there were no 4th grade words extracted from either grade. In the 2nd grade, the order was 1st grade (84%) > 2nd grade (8%) > 3rd grade (4%) = 4th grade (4%) in descending order, and the proportion of 4th grade words was the highest among all grades. In the corpus of narrative texts, the 1st grade had only 1st grade words (100%), the 2nd grade had 1st grade words (96%) and 2nd grade words (4%), and the 3rd grade had 1st grade words (98%) and 0th grade words (2%). As with the corpus of expository texts, the 2nd grade had a higher grade of words than the 3rd grade in the narrative text corpus.
 Conclusions Based on the research results, the vocabulary grade of expository and narrative texts in middle school Korean language textbooks is appropriate and provided suggestions on how to utilize the results for the development of new textbooks and vocabulary education.