For scholars and policy-makers alike, deeper learning has been a promising paradigm for fostering students' interest in and mastery of science, technology, engineering, and mathematics (STEM). Deeper learning is assumed to result in a more thorough understanding of a subject that endures the test of time. To reach this level, a fascination with the subject matter is thought to be a critical motivational element. The focus of our study was to measure the two core consequences of deeper learning: the extent of knowledge integration and the level of fascination with the subject matter (in this case, science and technology). Using a sample of sixth graders from Greece, Finland, France, and Portugal (N = 1,261), we explored the measurement properties of the two newly developed instruments. Both of our deeper learning assessment tools showed satisfactory measurement properties (i.e. fit indices and reliabilities). More importantly, both tools were able to cover a broad range of integrated knowledge and fascination, and thus, they can be used to differentiate between sixth-grade European students with low to high levels of fascination and knowledge. These properties of our assessment tools and their out-of-the-box availability will help foster more empirical research and the development of the deeper learning paradigm.