Competency-based teaching should be promoted to prepare students for future society. Teachers, however, experience difficulty with teaching competency. Research on curriculum materials, including teaching guides, suggested that they could provide ample opportunity for teachers’ professional development, when carefully designed to be educative. The current study sought to understand educative opportunities for competency teaching presented in high school mathematics teaching guides. For the analysis, educative curriculum material was used as a theoretical framework. The results showed that the teaching guides provide supports for limited kinds of educative opportunities only. Similar patterns were observed through out each units from the curriculum. In addition, the range covered by each kind of support was narrow, curriculum designers’ intentions are not communicated in most cases, and instructions for implementations are often omitted. These findings indicate that high school teaching guides require significant amount of revision. To make such revision happen, redesigning curriculum writing process might be necessary.