Experiments serve different purposes in chemistry education ranging from illustrating a certain subject matter to providing data for school-based research projects. When students use these experiments to collect data and draw conclusions, it is important that these experiments are valid. In this study, a new experiment for the determination of the explosiveness of dusts using a Low-cost-Hartmann apparatus (LC-HA) was developed for high school students. Which similarities and differences can be found between the data of developers and prospective users of the experiment? What is the added value of designing and applying a round robin test to a high school experiment? A round robin test including developers (n = 5) and prospective users (n = 54) is carried out. Data are collected from experiments with two different flour dust concentrations. Accuracy, precision, and variance are calculated for each group and compared between groups. There are similarities and differences between the data of both groups. For the lower concentration of flour dust, there are significant differences between the results of the two groups. For the higher concentration, there are no significant differences. Thus, carrying out a round robin test including both developers and prospective users benefits both groups. The developers gain insights into the application of their method. The prospective users receive information about their performance and the validity of their data. In the future, participation in round robin procedures should also be used as an opportunity to promote students' knowledge about and skills for validation.