The aim of this study is to assess a lesson observation tool which is used to evaluate teaching and learning process in secondary schools so as to enhance active pedagogical paradigm. The tool was established in 2017 to replace the school inspection observation tool that has been in practice for several years. The study was guided by three objectives which include: (i) to determine the merits of the tool; (ii) to examine challenges that are faced by school quality assurance officers when implementing the tool; (iii) to get suggestions from the users on improving the tool. Qualitative approach was used as a method of data collection and data analysis. The total sampled respondents were 21, 10 from Eastern zone and 11 from Dar Es Salaam zone. The whole population was 51 and all were school quality assurance officers from the named zones who are also teachers in profession. Data was collected through semi structured interview and each respondent was interviewed individually by the researcher in the offices of the respective zones located in Dar Es Salaam and Morogoro. The researcher made analysis of data and some respondents were directly quoted. The findings of the study revealed that the tool is important to school quality assurance officers as it leads, guides and acts as a roadmap for evaluation. It gives uniformity in the process, report writing and enables them to provide useful feedback to teachers. The three main identified challenges regarding the tool include, the mismatch between some sections in the lesson observation tool and judging criteria; time limit to make lesson observation; lack of teachers’ awareness about the tool, which is used to evaluate teaching and learning process. The study concludes that the lesson observation tool plays a vital role in evaluating and promotes quality teaching and learning, hence provision of quality education in the country. The study recommends that the Ministry of Education, Science and Technology and the policy makers to review the lesson observation tool so as to overcome the challenges that are affecting it for the purpose of improving teaching and learning process.