The integration of Technological Pedagogical Content Knowledge (TPACK) into instructional design is pivotal for teachers. This intricate knowledge framework encompasses the interplay between technology, pedagogy, and subject matter, profoundly impacting the multifaceted aspects of student learning, encompassing knowledge acquisition, skill development, and the cultivation of desirable attributes. This research at hand adopts an exploratory approach, examining two sample groups: 1) Science teachers from secondary schools under the Northeastern Region of Thailand during the academic year 2565–2566, totaling 124 individuals, and 2) Secondary school students receiving instruction in science-related subjects from the aforementioned teachers, with a minimum of one classroom involved. Data collection tools include a survey on TPACK, a scientific competency assessment, and semi-structured interviews. Statistical analysis employs mean, standard deviation, and content analysis. Testing of hypothesis uses One-Way Analysis of Variance (One-Way ANOVA). The study reveals that students taught by science teachers with varying levels of TPACK exhibit statistically significant differences in scientific competency at a 0.05 significance level. When comparing scientific competency with TPACK levels of teachers, statistically significant differences at the 0.05 level are found in two pairs: 1) the Adapting level and the Advancing level and 2) the Exploring level and the Advancing level.