A Dissertation Submitted in Partial Fulfillment of the Requirements for Award of the Master Degree of Education at Mzumbe University. 2016The research aimed to examine the impacts teachers‟ workload allocation on teaching and learning effectiveness of science subjects in secondary schools. The research was a case study design covering Hanang District Council. A sample size of 101 respondents was obtained by using both simple random and purposive sampling techniques of which both primary and secondary data were collected by using interview, observation, focus group discussion and documentary review and analyzed qualitatively using content analysis. The data were collected from teachers, students, academic teachers head teachers and DSEO from selected secondary schools of Endasak, Gitting, Chief Gidobat and Endagaw. The report has shown the increase crisis in teachers‟ workload allocation to science teachers and has been identified as consequences to the poor academic results among students in secondary schools in Tanzania. The report have shown all respondent heads of school, academic teachers, science teachers DSEO and students have agreed to the contributing effects of teachers workload on teaching and learning effectiveness. Among prevailing causative factors of teachers workload is shortage of science teachers to visited school where the number of science teachers was very few compared to arts teachers. Also the observed issues were shortage of teaching and learning materials including lack of laboratory with equipments to make practices. But also the other observed case was inability for the academic teachers to distribute working load among science subjects‟ teachers due to few number of science teachers which led to some of science subjects like mathematics and physics being left without having allocated to any teacher. This has resulted to students fail to complete syllabus, poor performances, lack of preparations among teachers, poor concentration in marking class tasks and assignment and fail to implement students centered approach methods of teaching. These among many were explained in this report. The results revealed that, presence of heavy workload has lead to lack of motivation to both teachers and student.