Research on the ontogenic and didactical obstacles vocational high school
students face in solving counting rule problems has been limited. Ontogenic
obstacles involve students' readiness, while didactical obstacles concern the
sequence and presentation of instructional materials. Therefore, teachers
must consider both when developing effective materials. This research aims
to describe the ontogenic and didactical obstacles experienced by vocational
high school students in solving counting rule problems. The participants of
this study were 24 grade XII students from a public vocational high school in
Cirebon. Using a Didactical Design Research (DDR) approach, this qualitative
study focuses on the prospective analysis stage, examining these obstacles.
The research instrument included five diagnostic essay questions and
interview guidelines. The results revealed that students encountered
instrumental-type ontogenic obstacles, particularly in understanding
factorial operations. Additionally, didactical obstacles arose from
incomplete teaching materials and improper notation, which led to learning
barriers. This research offers valuable insights for teachers and researchers
in designing instructional materials, especially for