The understanding of learning materials by students is the primary goal of education. However, this is not easily achieved by students. Teachers must make various innovations so that students can easily grasp the learning materials. Free-falling objects are one of the main topics in physics. Learning materials can be delivered through project-based activities in the classroom. Through class projects, empirical research can be conducted by both students and teachers. This article presents the tools and testing results related to the motion of granular materials as project-based learning. The flow rate of granular material in this project will illustrate the relationship between distance and time in free-fall motion. Therefore, this research designs and constructs a granular flow rate measurement system based on multiple sensors and a microcontroller to demonstrate the concept of free-falling objects through project-based learning. The method used is the design and construction of a device consisting of electronic and mechanical systems. The granular motion will be detected by the sensors. The main part of the electronic system consists of a microcontroller and five infrared sensors, which include five transmitters and five receivers. The mechanical system consists of a granular holding platform. Several types of granular materials are used for testing the flow rate measurement system. The lowest flow rate among the tested granular materials is around 70 grams/s for basil seeds, and the highest flow rate is for colorstone, with a flow rate of around 200 grams/s. The results also align with the basic physics concept of freefalling objects, which states that velocity increases as they approach the earth's surface due to the influence of gravity and distance. With the results obtained, this project-based learning device can be used to validate existing theoretical concepts.