This study aims to develop orthography education contents by investigating spelling errors in middle school students. Fifty first-year middle school students participated in this study. A total of 119 error types were collected, and they were classified into two groups: (1) for understanding principles of orthography, related to liaison and phonological processes, and (2) for promoting visual-orthographic skills. Based on these two groups, educational contents were developed, and the author discusses how they should be organized.