Exploring rotations by a modified fidget spinner and a smartphone

We present an educational activity, aimed at the exploration of rotational motion through the use of a modified fidget spinner and a smartphone. We analyze the physics concepts that are involved in the proposed experimental activity, such as angular velocity and moment of inertia, showing that it is possible to transform a well-known popular toy into an opportunity to teach/learn physics concepts, by performing easy and valuable physics experiments in classroom at undergraduate and first-year university laboratory.