This article describes the construction process and evaluation of the Agile Constructionist Mentoring Methodology (ACMM), a mentoring method for guiding software development projects in the high school. The need for such a methodology has arisen due to the complexity of mentoring software project development in the high school. We introduce the ACMM and suggest a year-long mentoring template that includes the practices required for the actual mentoring process. The evaluation of the ACMM reveals that the methodology addresses each of the challenges teachers cope with during the mentoring process, which were identified in the first phase of the research.