eng Science and Education Publishing American Journal of Educational Research 2327-6150 2026-10-26 14 10 321 325 10.12691/education-14-10-1 EDUCATION202614101 article Ace Michael B. Magalso acembmagalso@gmail.com 1 Ma. Teresa M. Fajardo 2 La Paz National High School, La Paz, Agusan del Sur, Philippines2College of Science and Technology Education, University of Science and Technology of Southern Philippines, Cagayan de Oro City, Philippines 1La Paz National High School, La Paz, Agusan del Sur, Philippines2College of Science and Technology Education, University of Science and Technology of Southern Philippines, Cagayan de Oro City, Philippines This qualitative descriptive study examined how secondary chemistry teachers demonstrate pedagogical content knowledge (PCK) and how the resulting profile can inform professional development. Eleven of 13 chemistry teachers in La Paz District, Schools Division of Agusan del Sur, met the inclusion criteria and participated. Data from an open-ended PCK questionnaire and focus group discussions were analyzed thematically; a supplementary seven-point self-assessment checklist was used descriptively to contextualize the qualitative evidence. Teachers reported checking prior knowledge, using diagrams, models, analogies, demonstrations, simulations, and familiar examples, aligning lessons with curriculum competencies, and using questioning, feedback, and reteaching. Stronger accounts connected a specific student difficulty with a chemistry representation, an instructional adjustment, and evidence of subsequent understanding. Development needs centered on more precise diagnosis of misconceptions, explicit movement among macroscopic, submicroscopic, and symbolic representations, contextualized planning under resource constraints, and clearer documentation of how assessment evidence changes instruction. The checklist was generally positive (overall item-weighted mean = 6.32), with Chemistry Content Representation lowest among the reported domain means (6.20); these self-ratings were interpreted as supplementary rather than as verified proficiency. The findings support sustained, chemistry-specific professional development organized around collaborative lesson design, diagnostic assessment, feasible practical work, coaching, classroom application, reflection, and revision. https://pubs.sciepub.com/education/14/10/1/education-14-10-1.pdf pedagogical content knowledge chemistry education teacher professional development instructional representations formative assessment Philippines