In this study, an simulation app was developed as one of the methods to help learners better understand the eight process scheduling policies of multi-programming. In learning, an app in the form of a simulation should provide a realistic environment and allow learners to practice. To do this, the needs of the learners were investigated and analyzed, and the purpose was set, designed, and programmed based on the learners' understanding. And it was shown that the apps as a tool to simulate the created eight scheduling policies are performing well. In particular, it was shown that the problem of not having a step-by-step various diagram and explanation for step-by-step various inputs, which is a limitation of paper textbooks, can be solved using these tools.