In the master class, adults will assemble a scientific toy and see how a simple physical phenomenon turns into a visual trick. The cube will move along a vertical string "at the command" of the participant, and the secret of friction will become clear through practice, experimentation, and an easy game mechanic that can be easily repeated at home. Sometimes physics is best revealed not through formulas, but through an object that can be assembled by hand and immediately tested in action. Participants will create a scientific toy based on the phenomenon of friction: the cube will descend along a vertical string from one hand to the other, as if responding to human commands. This format is especially good for those who enjoy clear experiments and practical activities. Instead of lengthy theory, there will be work with simple materials, observation of movement, and gradual unveiling of the mechanism. At first, it seems that the cube behaves almost magically, but behind the effect lies a precise physical principle. When the participant understands why the toy obeys, an ordinary object turns into a small laboratory. All entertainment in St. Petersburg is gathered on our website.