Putri Wulan Dhari
Writing proficiency is an essential competency in higher education because students are expected to produce academic texts that comply with the rules of Standard Indonesian. However, previous studies have primarily focused on general language proficiency, while evidence regarding students’ mastery of fundamental linguistic rules across orthographic, morphological, and syntactic domains remains limited, particularly in teacher education programs. This study aimed to examine students' mastery of basic Standard Indonesian language rules in the Primary School Teacher Education (PGMI) Program at IAIN Takengon and to identify the linguistic domain in which students experienced the greatest difficulty. This study employed a descriptive mixed-methods design, combining a questionnaire with follow-up interviews to explain the quantitative findings. The participants were 44 PGMI students at IAIN Takengon selected through purposive sampling. Data were collected using a structured questionnaire assessing students’ knowledge of Standard Indonesian language rules and semi-structured interviews to obtain participants’ explanations of the observed learning difficulties. Quantitative data were analyzed descriptively, while qualitative data were analyzed using thematic analysis to support the interpretation of questionnaire results. The findings indicate that syntax-related items produced the lowest proportion of correct responses compared with orthographic and morphological items. The most frequent difficulties involved identifying sentence ambiguity, recognizing appropriate sentence structures, and avoiding redundancy. Interview responses suggested that these difficulties were associated with limited understanding of grammatical rules, the influence of non-standard language use in daily communication, and insufficient opportunities to practice academic writing. The study concludes that syntactic competence represents the most challenging aspect of Standard Indonesian among the participants.