PRIMM is an approach to teaching programming at K-12 that facilitates the structure of lessons in a purposeful way. PRIMM stands for Predict-Run-Investigate-Modify-Make, and draws on recent research in programming education. In particular the PRIMM approach recognises that starting with existing code and being able to explain what it does gives novice programmers the confidence to write their own programs. Using the PRIMM approach, teachers can devise scaffolded and targeted tasks for students which helps engender understanding, particularly for those who may have previously struggled to understand programming concepts. In this techniques paper, we consider what PRIMM is, and the experiences that teachers have had of using the structure in the classroom. PRIMM materials have been trialled in schools in a study involving around 500 students aged 11-14. From interviews with nine participating teachers we have found that teachers particularly value the collaborative approach taken in PRIMM, the structure given to lessons, and the way that resources can be differentiated. We propose that PRIMM is an approach that could be adopted in all phases of programming education as well as in teacher training
