Project-Based Green Hydrogen Education in Portuguese Secondary Schools: An Exploratory Group-Level Pre–Post Assessment of Knowledge

The deployment of green hydrogen technologies requires not only technological development but also adequate scientific and technological knowledge among future generations. This exploratory study evaluates group-level differences in hydrogen-related knowledge before and after a project-based educational programme implemented during the 2025/2026 academic year in four Portuguese secondary schools. The programme combined introductory activities on the green hydrogen value chain, scientific research and communication, development of scientific posters, and the construction and optimisation of hydrogen-powered remote-controlled vehicles. Knowledge was assessed using the same questionnaire before and after the programme. The baseline assessment included 106 students, while 91 completed the programme and 85 participated in the final assessment. Fourteen knowledge-oriented items were included in the analysis. The mean proportion of correct responses was 75.7% before the programme and 85.7% afterwards, corresponding to a difference of 10.0 percentage points. The largest difference was observed for questions addressing hydrogen-related challenges and future deployment (+20.9 percentage points), followed by production and energy (+10.9 percentage points). Particularly large differences were found for fuel-cell operation, hydrogen volumetric energy density, and hydrogen transport. The proportion of “I do not know” responses decreased from 15.5% to 5.0%. Although the unmatched group-level design does not allow individual learning trajectories or causal effects to be determined, the findings indicate higher group-level knowledge scores following the educational programme, particularly for more technically demanding hydrogen-related concepts.