The glass-transition temperature (Tg) and degree of crystallinity (Xc) are important properties of polymers. However, for some polymers, current techniques have some difficulties in measuring Tg and Xc, particularly for as-prepared films without damage. Here, we develop a new technique to simultaneously determine Tg and Xc by measuring the restitution of a ball on an intact polymer film or sheet as a function of temperature. Demonstrating with eight different types of polymers, we show that Tg is the onset of the decrease in restitution, and Xc is the minimum restitution for semi-crystalline polymers with Xc up to 50%. Our simple yet versatile technique could provide a useful tool to measure challenging Tg and Xc of films and sheets by the conventional methods.