The use of portfolio in monitoring students’ authentic learning process has gained momentum in recent years by which this study sought to assess its extensiveness in secondary schools in Moshi District, Tanzania. The study addressed extensive usage of teacher’s portfolio in reflection of Physics subject teaching strategies. Guided by the Reflective Practice Theory (RPT) the study employed a convergent design under a mixed-methods research approach. The target population for the study consisted of 2,830 individuals including; heads of schools, physics teachers, students and District School Quality Assurance Officers (DSQAO) in 61 secondary schools. Simple random, stratified random, and expert sampling techniques were used to obtain DSQAO, heads of schools, Physics teachers and students making a total of 363 respondents. The validity of research instruments was ensured by research experts in the faculty of education specialized in Assessment and Evaluation at the University. The reliability of Likert scale items in questionnaire was assured through Cronbach’s Alpha coefficient which had outputs of .84 and .79 for teachers' and students respectively. The trustworthiness of qualitative data collection instruments was established through peer debriefing and triangulation. The quantitative data were descriptively analyzed in percentages, and frequencies, mean scores while qualitative data were analyzed thematically. The study adhered to ethical rules in research such as: anonymity, informed consents and confidentiality. The study found that although teachers are preparing portfolio documents, doubts regarding the organization and timely accessibility of these documents hinder their ability to enhance teaching and learning. The study concludes that teachers prepare documents for teaching and learning in physics, but improper portfolio organization remains a threat to providing constructive feedback for students' physics achievement. The study recommends proper organization and compilation of portfolios for effective tracking of students' learning progress.