This paper provides a systematic review of instruments that have the potential to measure the quality of project-based science and technology (S&T) learning environments in elementary school. To this end, a comprehensive literature search was undertaken for the large field of S&T learning environments. We conducted a horizontal bottom-up analysis of the aspects measured by the retrieved instruments and their operationalisation. We distinguish 11 components. The most frequently evaluated components are prior knowledge and backgrounds, connection with reality, science as inquiry and level of initiative and group work. Overall, the results suggest a considerable diversity in the operationalisation of the components found. Particularly, for connection with reality, science as inquiry and level of initiative and group work, this is related to (1) the object of measurement (e.g. variety in aspects evaluated) and (2) the extent to which the used concepts are clarified. Consequently, some scales, items and questions were found to be a closer fit with aspects of project-based learning environments than others. Additionally, most of the retrieved instruments cover science and not technology or project-based education. This review can be used when searching for a scale, item or question to measure particular aspects of S&T learning environments.