Snap discs made of bimetal have a lot of technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed (~3.5 m/s), the acceleration (~30000 m/s²) and the lower and upper snap temperature (~31 °C; ~99 °C). High speed videos give even deeper insight into the jump.