One significant component that has a demonstrable impact on students' achievement is the professional competence of teachers. The study employed a sequential-explanatory research design, a mixed research approach, and a pragmatic worldview. Semi-structured interviews, standardized scale tests, and document analysis were used to gather data. The populations included 60 teachers and 2400 students for quantitative study and 19 respondents for qualitative study. Document analysis, inferential and descriptive statistics, and thematization procedure were used to analyze the data. Out of the 313,295 teachers that took part in the testing between 2017 and 2019, 74,772 (24%) met the minimal criterion (62.5%), and only 14% had a license. There was a correlation (r =0.89, P < 001) between the academic achievement of students, the competency of teachers, and their licensing exams. Teachers' preparation at higher education institutions, their academic background, their socioeconomic background, their job satisfaction, unavailability of resource, sand lack of intervention were the key obstacles. Creating a professional development program for teachers who are teaching on the job is beneficial.