This project engaged Ghanaian secondary pupils in authentic science and engineering activities by using model biodigesters that reduce organic waste and produce biogas and fertiliser. The pupils' activities paralleled scientists' activities, such as asking research questions and designing experiments. Our study included two cohorts of Ghanaian pupils and US and Ghanaian university students (Cohort I--summer 2022/Cohort II--summer 2023) who worked together in an after-school science club. Our mixed methods approach incorporated a pre-test and post-test, interviews, and project product analysis. Pupils reported an awareness of differences between this project and their regular science classes. In both cohorts, results revealed a high impact on communicating information; using data to answer research questions; asking questions and defining problems; and planning and carrying out investigations. Lower impacts were observed on obtaining and evaluating information; constructing explanations and designing solutions; analysing and interpreting data; and collaborating through argumentation. The results show that science educators should utilise authentic science activities to help students develop science and engineering practices.