The main objective is to provide teachers with technology-enhanced formative assessment instruments (TEFA) on how to guide and evaluate STEAM and CT competences within transdisciplinary activities. Our previous KA2 Erasmus+-projects have successfully proven the value of a STEAM-approach, but we noticed a struggle and a need concerning the guidance and evaluation of the students (9-15 year) during the activities by teachers. Technology-enhanced formative assessment reflects a promising approach.