Extended Abstract Introduction One of the most important social institutions in any country is the Education system. Teachers are part of the human resources of the Education system and since they have the closest interaction and influence on students, they are of utmost importance. The teacher is a very crucial component in the education system, and any action taken to provide and train them directly affects the quality of the educational system However, one of the problems faced by the education systems in some countries around the world has been the shortage of human resources. The aging population in industrialized countries threatens the sustainability of public finances, leading governments to increase the legal retirement age. In Iran the large number of retired teachers and the imbalance in teacher recruitment have created challenges in recent years as well.Therefore, the aim of the present study is to explore the lived experiences of retired teachers who have been called back to work and are currently teaching, to identify the advantages, benefits, as well as problems and challenges faced by teachers in teaching after retirement. Method The present study has a qualitative approach and is of the phenomenological type. The target population cpmprised retired teachers who are currently part-time teachers. The research instrument was an interview, and purposive, criterion-based sampling was used, and 11 teachers were interviewed . The inclusion criteria were the individuals’ employment as teachers after retirement, and the exclusion criterion was the lack of willingness to participate in the interview. It is worth noting that after 10 interviews, the data reached theoretical saturation, however, the interviews were continued up to 11 participants for greater assurance. Interviews lasted for an average of 40-60 minutes. The research instrument was a semi-structured interview. The Data were analyzed using Colaizzi’s method, which consists of seven steps. The method used to determine the credibility of the data was “triangulation” (Moon, 2019). In this regard, different researchers and professors were involved in the data analysis. To ensure the accuracy of the findings from the researchers, the participants, or the report readers’ perspectives, techniques such as member checking, peer review, intercoder agreement, the participatory nature of the research, and the researchers’ reflexivity were used. Findings Based on the research findings and the coding of interview sentences and themes, from the total of two research questions, six main themes and 39 sub-themes were identified. The merits of employing retired teachers were identified in three main themes and 26 sub-themes.The advantages related to the retired persons were: improvement in physical condition (which includes improvement in mental health, increased social interactions and sense of belonging, restoration of order in the individuals’ life, receiving respect and attention, and no financial need), teaching and classroom management skills (which includes teaching without anxiety, ability to convey content in the best possible way, sufficient mastery of the subjects, designing effective assignments and questions, coherent and organized teaching process, use and creation of efficient methods, teaching according to student characteristics, skills in classroom management, reduced concerns and stress), communication and interpersonal skills (which includes influencing parents, being patient, compassionate and responsible, interest, attention to the comprehensive development of students, maintaining a balance in affection and intimacy with the student, sufficient knowledge of the student characteristics, the ability and skills to quickly diagnose students’ problems, freedom of action, having enough time to deal with matters, positive and reciprocal interaction between retired teachers and less experienced teachers). The challenges and problems of retired teachers engaged in teaching were identified in three main themes and 13 sub-themes, Individual and interpersonal challenges (which includes physical problems, being outdated concern about the negative attitude of students, opposition from those around them, and lack of competence and efficiency of some retirees), organizational and administrative challenges (which includes low salaries, delayed payment of wages, lack of attention to the problems of retirees, lack of an evaluation and selection system in employing retirees), social challenges (which includes non-acceptance and inability to adapt to the characteristics of the new generation, intolerance of generational changes, occupation of job opportunities by retirees, and the consequences of youth unemployment). Discussion It is recommended that retired teachers should not be re-employed for teaching duties as much as possible, and the process of teacher recruitment should be planned in such a way that ensures the presence of young and capable human resources in the classrooms. This does not mean that the capacities and experiences of the retired persons should be completely discarded; however, the retirees want and deserve attention, and it is believed that the retired teacher should not be re-employed in the previous position, instead their experiences should be used differently. In other words, instead of employing and inviting a retiree as simple teachers, for example, retired people should be invited to transfer their experiences to new teachers in workshops, or groups consisting of a retired person and a few less experienced teachers should be formed in such a way that they can exchanged ideas and participate in discussions related to teaching and teaching skills. Ethical considerations Aligned with the Declaration of Helsinki and its updates, this study upheld ethical standards, including confidentiality, informed consent, and voluntary participation. Data were processed anonymously, and participants were guaranteed that interview responses would remain strictly research-oriented. Contribution of authors This article was prepared with the opinion and participation of the supervisor and his cooperation. Funds In terms of financial resources, this research does not have any dependence on governmental and non- governmental institutions and organizations and has not received any financial support. Conflict of interest There is no conflict of interest between the authors of this article. Following the principles of research ethics In this article, all rights related to research ethics have been observed. All the members of the research sample participated in the project with full consent and each member had full freedom and authority to withdraw from the research at any stage. Also, the principle of anonymity has been respected by all members.