Creativity is a broad and complex construct, difficult to define and to quantify, assumed to introduce new impulses into science education (STEM), and leading to better acceptance of science by adolescents. Therefore, increasing efforts are being undertaken to integrate traditional creativity (Arts), in modifying STEM to STEAM. Consequently, a valid way of empirically quantifying of creativity of adolescents is needed. In this study, part of a European initiative (CREATIONS), an 8item Likert-scale questionnaire quantifying individual creativity was administered to a sample of 2,713 students, aged 11-19 (M ± SD = 15.71 ± 2.24; 54.7% females), revealing two subscales: one, labelled Act, covering conscious and trainable cognitive processes; the second, named Flow, contained items describing elements of flow experiences, a mental state of creativity. Analyses indicated that there were no gender differences and that younger students' creativity scores were higher than those of older students. Recommendations for implementation in STEAM lessons are discussed. Creativity is a broad and complex construct, difficult to define and to quantify. Unlike other complex variables such as personality or attitudes, research into creativity quantifying is still disputed. Although personality has been measured since the 1940s (